When I have ChildTicketsPlugin installed with then TracTicketChangesetsPlugin, the changesets generated by TracTicketChangesetsPlugin for the ticket appear twice.
This is because the ChildTicketsPlugin is using the "attachments" id for it's div tag. The TracTicketChangesetsPlugin is filtering the template stream looking for this ID so it knows when to insert it's section, sees "attachments" twice, and inserts it's section twice.
Obviously, TracTicketChangesetsPlugin needs to be fixed as well, but ChildTicketsPlugin should use something unique for it's section id, like "childtickets" (line 135 or ):
snippet = tag.div(id="childtickets")
You can get the same effect by using the "changelog" id (line 211 of ):
snippet.append(tag.div(tablediv, buttondiv, id="changelog"))
Mind you, this could end up having the same effect if someone filters the stream on "changelog"! So, maybe you could create your own id instead?
Ultimately, some of these styles that people are going to want to use should be moved from CSS ids to classes, but this is obviously out of your control. :)
I'm also going to put a bug against TracTicketChangesetsPlugin.