Copying Electrolyze
PC version
Strixhaven Premiere Draft.
I cast Lead by Example
I cast Electrolyze
there is a 2/3, 2/1 and a 2/2 on the board. I split the first copy 1 and 1 on the 2/3 and 2/1. My plan was to deal 2 more to the 2/3 with the second electrolyze, but it would not allow me to only submit one target. Instead, I had to select two and split 1 and 1 again. This made it so only one creature died and I lost the game.

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RJMY#16475 commented
Ran into this issue just now. Used Repeated Reverberation, targeted two 1/1s with the original copy, tried to target Meteor Golem alone with a copy and Morbid Opportunist with the other copy, but I was forced to select two targets. I doubt it matters but I got the Electrolyze from Key to the Archive.