Elrond and Elros

[Encaitare]

Okay, guys, I have one of those dumb questions that just pops up in my mind every so often... were Elrond and Elros twins? The Encyclopedia of Arda says that they were both born c.525 of the First Age, but this doesn't mean that they were indeed twins.

I ask because I wrote a fanfiction about them, and since I couldn't find anything concrete I decided Elros was going to be a couple of years older and therefore help explain his choice of mortality. In a review I just received, the person told me they were twins, and it's just been bugging me. I *must* know because if they are indeed twins, I'll change the story -- I hate being wrong! Okay, enough rambling from me... someone please help!