Sounds very similar to Abstract, as suspected.
Marie Lu Vinh

Just tried Abstract. I don’t agree with you that Plant and Abstract are similar. Plant has more powerful conflict resolving. In Plant you don’t just select which version do you want to leave in your file, you can operate with artboards in Sketch directly, and combine new version! 
Also, Plant doesn’t obligate you to choose tracked/untracked changes, you decide what you want to commit now, and what later.
I recommend you to try Plant :-)

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