If you proliferate twice, you don't have to choose the same set of players and/or permanents to get additional counters each time
The big exception to this rule is Venat, Heart of Hydaelyn, which is an excellent rate due to how easy it is to trigger
Think of them like a stack of wanted posters, with only the topmost criminal being up for grabs at a given time
Talk About Simple
Padeem, Consul of Innovation is a powerful card that does a variety of things
Madam Mim, Foxs Chasing the Rabbit ability allowed me to return a character from the board to my hand, which meant I could bring back damaged ones or trigger powerful effects from cards entering the battlefield over and over - when Merlin, Goat, which gains a lore each time it enters and leaves the battlefield, turns up you can see where the game really starts