Every time you pause or pause and replace a set of Ads from within a multi-adgroup test result screen (Ads matched by either patterns or labels), that specific test result will be archived automatically in an archive. This will allow you to see a historical record of all changes you made.

An archived test result will record the action you took (a Pause vs Pause and Replace) as well as the replacement pattern (if any).

Archived test results are visible for multi-adgroup tests for both text and image Ads as shown here: