In beta, when specifying an already present attribute (i.e. recording date “1994-09” → “1994-09-06”) by batch adding it anew, the result is duplicate credits. In non-beta the credit “merges” OK.
Edit:
Disambiguations do not show. F.i. try manufactured by label PMDC and look for the French one.
Edit by @yvanzo: now tracked as [MBS-12966] Regression: Specifying an attribute to a relationship duplicates it - MetaBrainz JIRA