there can be several collection entries for each game and user
E.g., user ComtriS
has three entries for Blood Rage (170216
), for separate editions. Because merging will only keep the most recently updated, the game's rating will actually be lost in the database (and consequently be recommended).
Curiously, when excluding implementations, the recommendation vanishes: https://boardgamegeek.com/article/32301710#32301710
The solution should be that when merging, not just the most recent item should be kept, but instead properties should be merged too in an intelligent way.