With following steps, we can reproduce our problem:
1. developer 1: open resource files with rbEditor and select one entity
2. developer 2: add new entity to the same resource file and check in
3. developer 1: update the resource files (wich won't change the first view (summary view))
4. developer 1: add new entity using the summary view and check in
Result: developer 1 added its own entity and implicit deleted the new entity from developer 2
Ok, we understand this and always reopen rbEditor after updating files. But it would be nice, if it would not be necessary.