Is there a way to share APEX code between two managed packages in salesforce?

hello,

A couple of options exist between SVN (for example) and Ant.

1. SVN route, you could create a ‘shared code’ repo and utilise Externals, check out this link.
2.  Ant route, you can build an Ant script that explicitly pulls in (via the SVN tasks for example) source from different locations prior to deploying to your development and/or packaging orgs.