Better than a GIF or screenshots is step-by-step instructions on how to reproduce the problem. In 4.0.24 when I separate alpha for a slot, I can set keys for RGB or A separately, without an unwanted key being set for the other. Can you please explain how I can see the problem you are seeing?
We found a problem that may be related, where with slot alpha separate, if you click a key then another key, the alpha button shown in the tree properties for the second key shows the wrong alpha/color. If you click either color button, then it shows the right color. I don't believe this bug can result in unwanted keys being set. We'll fix it in 4.0.25 today!