What is the version of xEdit you are using?
TES5Edit 4.1.3b EXTREMELY EXPERIMENTAL (CDA61A13) starting session 2020-07-22 21:41:15

Describe the bug
Records with hardcoded FormIDs (i.e. anything with an object ID < 0x800, regardless of the FormID prefix) will override or inject into the hardcoded set of records that the engine reserves. xEdit, however, shows them as new records.

To reproduce
Steps to reproduce the behavior:

1. Download test.zip and install it with a mod manager (or manually) (SLE or SSE)
2. Open test.esp in xEdit and navigate to its only record at 0100000F
3. Observe that xEdit shows this as a new record
4. Make sure that test.esp is enabled and launch the game
5. Type player.additem f 100 and player.openactorcontainer 1, then hit Alt to see your own inventory
6. Notice that the gold has been renamed to 0x800 is not a safe region, meaning that the new record at 0100000F actually acts as an override

Expected behavior
xEdit should probably show this record as an override. Note that I've only confirmed this behavior for Skyrim LE and SE. Fallout 4 should not exhibit this behavior for version 1.0 plugins anymore. Older games should exhibit it, but I haven't tested it.