1999 $1 Note Back Side Error?

Nice find!

It does have a larger border than others, so, is this a keeper?

Looks like a misaligned first print (back of note) but is not truncated (missing part of the design where its cut off) and not seeing any part of the next notes design which are the ones with decent added value browsing through the book United States Paper Money Errors. The others like with just wider margins are considered minor and definately interesting to keep a few for a collection when uncirculated but likely have no or minor added value such as on ebay.

General info on misalignment/cutting errors:
Normal notes have an even border around the engraved picture on the front and back. Sometimes, when the sheet of bills gets out of alignment during printing, the note will have uneven borders, a truncated design or even part of the next note's design. Typically, misaligned notes will appear well-centered on one side and off-center on the other side.https://www.pmgnotes.com/news/artic...tember-2021/

An example of a misalignment:


Cutting errors happen when the sheets fail to align properly during the last stage of creating a banknote: the cutting process. Both sides of the note will be affected by this error. Typically, in order to qualify for a Cutting Error however, a small portion of the adjacent note must be visible or (when the error occurs at the edge of the sheet) a small portion of the note's design must be cut off. See the $5 bill here from series 2017a which has cutting error that affected both sides of the note https://www.pmgnotes.com/news/artic...tting-error/