Are there different Earths in Marvel like there are in DC?
Yes there are. With the idea being a major plot-point in many stories through out Marvel’s history. Especially in the recent Secret Wars (Secret Wars (2015 comic book)) and the lead up to it.
With them even having several titles dedicated to the idea of different or alternate Earths. Like Marvel’s What If? (What If (comics)) series. Which are normally told from the point-of-view of the Watcher (Uatu (Earth-616)), as he gazes into alternate worlds when pondering hypotheticals.
There is also the Exiles (Exiles (Multiverse)),
and their series. Which is just about a team going to alternate Earths
in order to help correct errors in the timeline. With each member of the
team normally being from different Earths.
And in general, Marvel operates their Multiverse (Multiverse)
under the idea that there are multiple universes, branching forwards,
parallel, and backwards through time. Meaning that their are alternate
version of the past, present, and future. Each operating as their own,
separate universe. Each with branches into the future.
Pretty much, you can find a series of alternate universes for any point and time.
And, short answer to your question… yes Marvel does have the idea of multiple Earths.