Can a fund manager (of a fund) be a venture partner for another fund without creating a conflict of interest?

The situation described is most likely a conflict of interest - but this doesn't guarantee it can't be done. Conflicts of interest are generally disclosed in a Fund's Limited Partner Agreement - and having any roles in other funds almost certainly fits.

In such situations, there will need to be an evaluation of potential outcomes of any conflicts even with disclosure in order to craft the proper language - we recommend consulting with an experienced fund formation specialist attorney for assistance.