The general rule to avoid these kinds of unresolvable conflicts is: don’t pass around references to values that might be inconsistent across systems. It’s like passing a pointer from one address space to a process in another; you just shouldn’t expect it to work. Either pass around the actual values or do calculations involving those values and replicate the result.
When dealing with distributed state think about the actor model.
Original title and link: Dealing With Distributed State (NoSQL databases © myNoSQL)