diff --git a/src/lib/documents/__tests__/extract-reads.test.ts b/src/lib/documents/__tests__/extract-reads.test.ts
index 37792100e..57fa54549 100644
--- a/src/lib/documents/__tests__/extract-reads.test.ts
+++ b/src/lib/documents/__tests__/extract-reads.test.ts
@@ -103,6 +103,24 @@ describe("runInboundExtraction over several reads", () => {
     expect(result.incomplete).toBe(false);
   });
 
+  it("keeps a value two reads list for different report dates, and merges it on the same date", async () => {
+    const page = (reportDate: string | null) => ({
+      content: JSON.stringify({ reportDate, facts: [observation("Hb", 14)] }),
+    });
+    // Two reports of different days, one value each with no date of its own.
+    const twoDays = await run(
+      scripted([page("2026-09-01"), page("2026-09-30")]),
+      reads(2),
+    );
+    expect(twoDays.facts).toHaveLength(2);
+    // A page without a date reads under the report's, as the lab scan does.
+    const sameDay = await run(
+      scripted([page("2026-09-01"), page(null)]),
+      reads(2),
+    );
+    expect(sameDay.facts).toHaveLength(1);
+  });
+
   it("keeps the lab scan's row cap, and says when a report holds more", async () => {
     expect(INBOUND_MAX_FACTS).toBe(OCR_MAX_ROWS);
     const reply = (r: number) => ({
diff --git a/src/lib/documents/extract.ts b/src/lib/documents/extract.ts
index cd821fd76..d48803484 100644
--- a/src/lib/documents/extract.ts
+++ b/src/lib/documents/extract.ts
@@ -293,8 +293,13 @@ function factPage(raw: ExtractedFactRaw, chunk: OcrChunk): number | null {
     : null;
 }
 
-/** The identity of a fact for the merge: the same fact in two reads is one. */
-function factKey(raw: ExtractedFactRaw): string {
+/**
+ * The identity of a fact for the merge: the same fact in two reads is one.
+ * A fact without a date of its own is keyed on the date of the report its
+ * read belongs to, as the lab scan keys a row, so the same value on two
+ * reports of different days stays two facts.
+ */
+function factKey(raw: ExtractedFactRaw, readDate: string | null): string {
   return [
     raw.type,
     raw.label.trim().toLowerCase(),
@@ -303,7 +308,7 @@ function factKey(raw: ExtractedFactRaw): string {
     (raw.unit ?? "").trim().toLowerCase(),
     (raw.referenceText ?? "").trim().toLowerCase(),
     (raw.dose ?? "").trim().toLowerCase(),
-    normaliseDate(raw.effectiveDate) ?? "",
+    normaliseDate(raw.effectiveDate) ?? readDate ?? "",
   ].join("|");
 }
 
@@ -345,9 +350,12 @@ export async function runInboundExtraction(
   let droppedFacts = 0;
   for (const { envelope, chunk } of reads.reads) {
     droppedFacts += envelope.droppedFacts;
+    // A read that prints its own date keeps it; the others read under the
+    // report's.
+    const readDate = normaliseDate(envelope.reportDate) ?? reportDate;
     const readKeys: string[] = [];
     for (const raw of envelope.facts) {
-      const key = factKey(raw);
+      const key = factKey(raw, readDate);
       if (seen.has(key)) {
         mergedDuplicates += 1;
         continue;