diff --git a/frontend/src/components/LeftoverMapPlot.tsx b/frontend/src/components/LeftoverMapPlot.tsx
index aa5440d58..ef6ab3044 100644
--- a/frontend/src/components/LeftoverMapPlot.tsx
+++ b/frontend/src/components/LeftoverMapPlot.tsx
@@ -174,7 +174,8 @@ function leftoverMapPlotAxisText(
  * comparison-graphic and rank labels rather than adding SPA translation debt.
  * ADR 0319 captions leftover-map distance on that comparison graphic using
  * the same localized composition boundary rather than adding another static
- * comparison-only translation key.
+ * comparison-only translation key. ADR 0320 names comparison coordinate ticks
+ * through the same composition boundary, preserving localized generic tick copy.
  * Never invent a leftover score.
  */
 export function LeftoverMapPlot({
@@ -300,9 +301,16 @@ export function LeftoverMapPlot({
           </text>
           {layout.ticks.map((tick) => (
             <g
-              key={`tick:${tick.axis}:${tick.label}`}
+              key={`tick:${tick.axis}:${tick.value}`}
               className="leftover-map-plot-tick"
-              aria-label={tf(LEFTOVER_MAP_PLOT_TICK, { axis: tick.axis, value: tick.label })}
+              aria-label={
+                variant === "comparison"
+                  ? `${t(LEFTOVER_MAP_COMPARE_PLOT_LABEL)}: ${tf(LEFTOVER_MAP_PLOT_TICK, {
+                      axis: tick.axis,
+                      value: tick.label,
+                    })}`
+                  : tf(LEFTOVER_MAP_PLOT_TICK, { axis: tick.axis, value: tick.label })
+              }
             >
               <line x1={tick.x} y1={tick.y} x2={tick.tickX2} y2={tick.tickY2} />
               <text
diff --git a/frontend/src/leftoverMapPlotLayout.test.ts b/frontend/src/leftoverMapPlotLayout.test.ts
index 0f2704da5..dedfc5801 100644
--- a/frontend/src/leftoverMapPlotLayout.test.ts
+++ b/frontend/src/leftoverMapPlotLayout.test.ts
@@ -206,6 +206,23 @@ describe("layoutLeftoverMapPlot", () => {
     expect(originAxis1).toMatchObject({ x: layout?.originX, y: layout?.originY, label: "0.00" });
   });
 
+  it("keeps distinct persisted coordinate ticks when their displayed labels match", () => {
+    const layout = layoutLeftoverMapPlot(
+      [
+        pair({
+          leftover_map_person_axis_1: 0.501,
+          leftover_map_item_axis_1: 0.504,
+        }),
+      ],
+      criterionLabel,
+    );
+    const matchingTicks = layout?.ticks.filter(
+      (tick) => tick.axis === 1 && tick.label === "+0.50",
+    );
+    expect(matchingTicks?.map((tick) => tick.value)).toEqual([0.501, 0.504]);
+    expect(matchingTicks?.[0]?.x).not.toBe(matchingTicks?.[1]?.x);
+  });
+
   it("does not invent drawing-scale leftover-map ticks on a rank-0 origin cell", () => {
     const layout = layoutLeftoverMapPlot(
       [
diff --git a/frontend/src/leftoverMapPlotLayout.ts b/frontend/src/leftoverMapPlotLayout.ts
index 5689e4a36..02f5ba9ba 100644
--- a/frontend/src/leftoverMapPlotLayout.ts
+++ b/frontend/src/leftoverMapPlotLayout.ts
@@ -227,17 +227,19 @@ function boundedCaptionY(y: number, height: number): number {
 }
 
 function uniqueCoordinateTicks(values: number[]): { value: number; label: string }[] {
-  const byLabel = new Map<string, number>();
+  const uniqueValues = new Set<number>();
+  const ticks: { value: number; label: string }[] = [];
   for (const value of values) {
     const label = formatSignedLeftoverValue(value);
     if (label === null) {
       continue;
     }
-    if (!byLabel.has(label)) {
-      byLabel.set(label, value);
+    if (!uniqueValues.has(value)) {
+      uniqueValues.add(value);
+      ticks.push({ value, label });
     }
   }
-  return [...byLabel.entries()].map(([label, value]) => ({ value, label }));
+  return ticks;
 }
 
 function leftoverMapCoordinateTicks(
diff --git a/tests/test_grouping_comparison_graphic_tick_contract.py b/tests/test_grouping_comparison_graphic_tick_contract.py
new file mode 100644
index 000000000..d0c3af61e
--- /dev/null
+++ b/tests/test_grouping_comparison_graphic_tick_contract.py
@@ -0,0 +1,42 @@
+"""Executable contract for coordinate ticks on the grouping-comparison graphic."""
+
+from pathlib import Path
+import re
+
+
+ROOT = Path(__file__).resolve().parents[1]
+PLOT_SOURCE = ROOT / "frontend" / "src" / "components" / "LeftoverMapPlot.tsx"
+LAYOUT_SOURCE = ROOT / "frontend" / "src" / "leftoverMapPlotLayout.ts"
+
+
+def test_comparison_graphic_names_ticks_with_distinct_accessible_copy() -> None:
+    """Comparison ticks compose existing localized comparison and tick copy."""
+    plot_source = PLOT_SOURCE.read_text(encoding="utf-8")
+
+    assert "LEFTOVER_MAP_COMPARE_PLOT_LABEL" in plot_source
+    assert "LEFTOVER_MAP_PLOT_TICK" in plot_source
+    assert re.search(
+        r'variant\s*===\s*"comparison"\s*\?\s*`\$\{t\(LEFTOVER_MAP_COMPARE_PLOT_LABEL\)\}:\s*\$\{tf\(LEFTOVER_MAP_PLOT_TICK,\s*\{\s*axis:\s*tick\.axis,\s*value:\s*tick\.label,?\s*\}\)\}`\s*:\s*tf\(LEFTOVER_MAP_PLOT_TICK,\s*\{\s*axis:\s*tick\.axis,\s*value:\s*tick\.label,?\s*\}\)',
+        plot_source,
+        re.DOTALL,
+    )
+    assert "LEFTOVER_MAP_COMPARE_PLOT_TICK" not in plot_source
+
+
+def test_tick_positions_come_from_persisted_coordinates_not_distance() -> None:
+    """Tick candidates remain the origin plus finite persisted ξ/ζ projections."""
+    layout_source = LAYOUT_SOURCE.read_text(encoding="utf-8")
+
+    assert "const axis1Values = [0];" in layout_source
+    assert "const axis2Values = [0];" in layout_source
+    assert "pair.leftover_map_person_axis_1 as number" in layout_source
+    assert "pair.leftover_map_item_axis_1 as number" in layout_source
+    assert "pair.leftover_map_person_axis_2 as number" in layout_source
+    assert "pair.leftover_map_item_axis_2 as number" in layout_source
+    tick_builder = re.search(
+        r"function uniqueCoordinateTicks\(.*?\n}\n",
+        layout_source,
+        re.DOTALL,
+    )
+    assert tick_builder is not None
+    assert "leftover_distance" not in tick_builder.group(0)