4-20 ma Wetting Scenarios

I have a project that has a large number of 4-20 ma analog inputs. In the past I have used a set of redundant power supplies and have individually fused each loop from the same source. With out a problem of cross talk. We now have a customer that is concerned about the cross talk in our solution and requires a regulator in each loop. Does anyone have a link to documentation supporting either scenarios. 1- A number of analog loops being wetted from a single source vs. 2- Separate regulators for wetting of each loop. Also has anyone had problems with cross talk using approach #1? Thank everyone for any support, Lou