Example of reason to change dialog id used by mod B:
Mod A (willingly) changes/fixes standard info with id 0001 from "Hello %PCName, how ar you!" to "Hello %PCName, how are you?". Fine.
Mod B wants to add a new copy of the info, correctly filtered for Caius Cosades only and ordered to be before the standard one, saying "Hello my dear %PCName",
But (ignorant or without realizing) instead of changing the new copy of the info made by CS with brand new id (e.g. 0010) changes the original one with id 0001 and then reorder it to be before, with the result of being incompatible with mod A