I think I've got both of these fixed for v18.
As for the repeated export groups, the problem is the apostrophe. We were not correctly handling it when we searched the xml for the group name, which caused us to not find that group in the xml file. When we didn't find it, we added it again. That will be correctly handled in v18. For now, you can work around it by naming your export group something else.
The Objective-C error in the import is a minor thing. It's not hurting anything for now and will disappear in v18. You can safely ignore it when you get it. Or you can continue as you were and create an export group that just excludes Objective-C.
Thanks for reporting these issues and helping me figure them out. If I hadn't known what you'd named your export group, I'd have gone crazy trying to reproduce the issue!