The suggested solutions of using unset and/or rename commands to remove or rename fields that contain a dot does not work.
Because the original source name must be specified as a field name one will have trouble getting a driver to encode it correctly. Using a driver that permits ignoring this problem (eg. C# with "CheckElementNames = false") causes the server to interpret the string as a dotted path and hence the unset or rename does not find the field at all (and does nothing).
At this time I do not know the solution to this problem but the suggested solutions certainly do not seem to be possible.