It all really depends on the agreement you have with your partner. Some consider anything developped under a company's employment or identity belongs to that company - some may argue that the developer has rights to it - probably not to often the case
If that were the case there'd be a lot more rich developers.
However if you want to keep a copy of whatever you develop - I wont tell anyone - just be sure that you're not sued later on if you plan on using it. -
But in my opinion the copyright would unfortuantely go to the company in corporate circumstances. You were hired or positioned to create something for them.
Sorry.
Cheers