I recently did a TreeShare from an Ancestry Tree online into RM. I started some cleanup and establish a few Groups so I knew areas to work on when I was back in TreeShare (primarily who to merge in the Ancestry file). Upon viewing the Master Source List I discovered several duplicated Sources. So I used the Lists > Source Lists > Automerge feature ...it counted to 53 then stopped and hung RM completely. Ctrl-Alt-Del & reopen RM and the TreeShared file.
After careful review to see if any of these were indeed duplicates (spelling or punctuation differences, I then proceeded to manually Merge these under the Source List. All went well in Manual Merge until I encountered the "U.S., Find A Grave Index, 1600s-Current" set of duplicate Sources (8 in total). When I attempted to Manually Merge the first two of these RM would again hang up/freeze completely. I even waited several minutes (> 45) and RM was still hung when I returned to check on it. At that point I got a window named "Cleaning duplicate sources..." with content of "Merged: 7", which leads me to believe the original entry of "U.S., Find A Grave Index, 1600s-Current" Ancestry Sources is the issue.
The first "U.S., Find A Grave Index, 1600s-Current" Ancestry Source entry has a large number of Citation linked Facts to it, the second one was without any Citations, the 3rd - 8th had a few Citations. I was subsequently able to delete the second entry and Merge 3 through 8 into one Master Source. When I attempted to Merge the last remaining small set of Citation entry to the first one, the RM program again appeared to hang/freeze.
My suspicions are there may be some upper limit to how many Master Source entries can be Merged together, or if not, then some sort of memory limitation in processing this Merge.
The visible text of each of these "U.S., Find A Grave Index, 1600s-Current" Ancestry Source entries is exactly the same:
Footnote: Ancestry.com, U.S., Find A Grave Index, 1600s-Current (Provo, UT, USA: Ancestry.com Operations, Inc., 2012), [Page].
Short Footnote: , U.S., Find A Grave Index, 1600s-Current, [Page].
Bibliography: , Ancestry.com. U.S., Find A Grave Index, 1600s-Current. Provo, UT, USA: Ancestry.com Operations, Inc., 2012.
Find A Grave. Find A Grave. http://www.findagrav.../cgi-bin/fg.cgi.
As of yet I am not sure of the repercussions in TreeShare on Merging the apparently identical Master Sources that did actually Merge. Hopefully The API will recognize those as the same if more of the same exact Ancestry Sources are brought over via TreeShare. Time will tell.
EDIT: The first "U.S., Find A Grave Index, 1600s-Current" Ancestry Source has 5499 listed Citations. Seems like an odd number to have in total.