On Sunday afternoon, I discovered that I had not latched the connecting gate across the two halves of the barn in the back field correctly, and the two goat groups had 100% switched places (but Herc stayed where he was). So I just closed the gate. I'll switch everyone back after the rain today or tomorrow.
Of course, this morning I found that the two redhead baby boys had sneaked back into "their" side of the barn and were very disoriented and unhappy to discover no moms when they woke up. I relocated the wanderers without too much trouble.