Yes, you can put the Platform behavior on as many different objects as you want. And technically, yes you could have different controls for them. Construct doesn't yet have controls for two or more players, but you could do it with key presses instead of control presses.
The Platform behavior has an action to ignore input (that ignores the default control scheme), which lets you control the object manually through other actions, such as setting the speed and all that jazz.
But without networking you'd have to have two players on the same keyboard using different keys though, so it's not very practical. I'd wait until there's multiplayer support, controller support, and online support before you have to worry about it.