re: GP_DIALOG 0/1 is a byte-identical duplicate; 2/3 is a structural pair

The two adjacent pairs with identical element sets split. 0/1 are the same 59 810
bytes stored twice -- a duplicate, not a language pair. 2/3, the DIFFICULTY build,
differ in size and in 2.77 % of bytes from offset 0x1BB while sharing every element
name, which is what a language pair looks like.

Control: entries 10/11, known to be two different dialogs, differ in 54.90 % of the
common prefix, so the comparator separates unrelated dialogs.

Supported, not proven, with the untested step named: I have not captured DIFFICULTY
in ja. That the two are ENGLISH and JAPANESE rests on the disc's convention, not on
a capture of this screen. This partially restores a claim I withdrew, at lower
strength than the original phrasing.

Also records a refutation attempt on the port's BGM_103 exclusion: it survives and
is tighter than they stated -- of 32 census rows, exactly one bank carries EITHER
wave size, not merely both.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Wuu56cE8vJGTBtn1ppsk8v

docs/re/data/dialog-0-1-is-a-duplicate.txt

@@ -0,0 +1,37 @@
+# Are GP_DIALOG entries 0/1 and 2/3 language pairs or duplicates? 2026-08-31.
+# ✅ ANSWERED, and the two cases SPLIT.
+#
+# They are the only two adjacent pairs in GP_DIALOG with identical element sets;
+# every other adjacent pair is two unrelated dialogs
+# (difficulty-is-a-dialog.txt). Identical element NAMES are equally consistent
+# with a language pair and with a byte-for-byte duplicate, so it was left
+# untested. The bytes decide it.
+#
+# ✅ CONTROL: entries 10/11 are known to be two DIFFERENT dialogs (stage 10 vs
+# stage 02). They differ in 54.90 % of the common prefix and in size. A
+# comparator that cannot separate two unrelated dialogs cannot judge two similar
+# ones -- this one can.
+#
+#   entries 10/11  sizes 7 072 448 / 6 788 820   54.90 % of bytes differ
+#   entries  0/1   sizes    59 810 /    59 810    0.00 % -- BYTE-IDENTICAL
+#   entries  2/3   sizes 8 136 936 / 8 124 856    2.77 % differ, first at 0x1BB
+#
+# ✅ ENTRIES 0/1 ARE A DUPLICATE. Same size, zero differing bytes. Not a language
+# pair -- the same 59 810 bytes stored twice.
+#
+# 🟡 ENTRIES 2/3 -- THE DIFFICULTY BUILD -- ARE NOT. Different sizes, 2.77 % of
+# bytes differing from offset 0x1BB, while sharing EVERY element name. That is
+# what a language pair looks like: one layout, one element set, and a small
+# fraction of the payload differing where the glyphs live.
+#
+# ⚠️ SUPPORTED, NOT PROVEN, and the untested step is nameable: I have not
+# captured DIFFICULTY in `ja`. What is established is "two builds, same element
+# names, ~97.2 % identical bytes"; that they are ENGLISH and JAPANESE rests on the
+# disc's pattern of shipping screens twice per language, not on a capture of this
+# screen.
+#
+# 📌 This partially restores a claim I withdrew. I called 2/3 "an EN/JP pair" as a
+# bare assertion, and withdrew it when sylpheed-port showed adjacent GP_DIALOG
+# entries are generally unrelated. The withdrawal was right -- I had no evidence
+# then. This is the evidence, and it is weaker than the original phrasing: a pair
+# by structure, a LANGUAGE pair by inference from a disc-wide convention.