P2P replication, Null, empty string conflicts

I am using transactional, Peer to Peer replication on SQL Server 2008 R2, Enterprise Edition. Occasionally, I see updates in the application log that look like for whatever reason the end user has changed a Null field to an empty string. Not sure why - I will leave that to the developers. But, sometimes when this happens, an Update/Update conflict shows up in Replication. The conflict note always shows that the row was changed at both nodes, even though it wasn't. I would appreciate any insight as to why this might be occurring. It doesn't result in any data discrepancies, but is more of a nuisance in that I have to research the conflict to make sure everything is OK.