Start with a mod: test1, make a copy of it: test1copy, compare test1 & test1copy in tes4gecko & tes4edit, they match. Also tried with making an actual change to the mod and then comparing to see if only the known change is shown.
Load test1 into the tes4conset, not make any changes and just save it as is, exit. Then compare the newly saved test1' versus test1copy, the two no longer match. Tes4edit shows a change in world space, but Tes4gecko shows changes in cells, dialog & world space. Other mods used as samples also no longer match but will have different changes. This happens with mods with and without the 'inter-grid connections' warning.
Having tested 6 known mods, 4 of them have changes. The only common factor that I have found (stumbled on) in the 4 mods that have changes is that they have PGRD records. UOP3.2.0, UOP3.2.5, expanded hotkeys, Kragenir's Death Quest have changes while droplittorches & better letters don't. I've tested more mods but the names I use are not recognizable, because of merges.
This is with; oblivion with SI 1.2.0416, tes4conset 1.2.404, tes4gecko 15.2 & tes4edit 2.5.3, which I hope are the correct versions of each. This happens with straight and obse(18b6d) launched tes4conset.
I have uninstalled tes4conset, cleaned folder and registry debris and then reinstalled tes4conset. I still get the same type of changes between copies of the same mod after saving one with tes4conset.
Any advice or an obvious operator error correction would be appreciated.