Sorry, but you really need to be careful with your wallet files when dealing with any cryptocurrency. The automatic backups help reduce the likelihood of losing funds but aren't a replacement for keeping your own backups and maintaining proper security.
We've spent the last few weeks working on fixes for these problems. The latest builds should not be affected, have you upgraded to the lastest dashd and sentinel ? If so you should not see invalid masternodes in the ENABLED state.
That wouldn't be easy to do. Voting on superblocks is automated and deterministic so the vast majority of masternodes should have voted for F1. You would need to control many masternodes to cause F2 to win instead.