Posting from multiple Raiser's Edge databases to multiple Financial Edge databases from a workstation (even in a 1:1 configuration) is not supported by Blackbaud.

In the registry on a workstation (or terminal server, etc) there is only one ODBC connection for the GL integration, and it only references a single FE database at a time.  Even if there are two RE7 databases and two FE databases, and you are trying to post from RE1 to FE1, and RE2 to FE2, each RE7 will always post to whichever FE database is listed in that single registry key.

If multiple Raiser's Edge databases need to integrate with only ONE Financial Edge database, review How to integrate multiple Raiser's Edge databases with one Financial Edge database