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 saved automatically in an archive. This will allow you to see a historical record of all changes you made.

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

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