Not sure if this can be considered a bug.
When merging 3 posts with 4, 3 and 2 likes respectively in this exact order, the final post gets only 2 likes. I expect to see 4 likes, if not more (should be DISTINCT likes of all posts).
Example who liked posts:
Post 1: A, B, C, D (4 likes)
Post 2: A, B, E (3 likes)
Post 3: C, D (2 likes)
Resulting likes should be: A, B, C, D, E (5 likes)
P.S. A, B, C, D and E are nicknames who liked the posts.