Saxophone help?

Is there a way to play two notes at the same time on an alto saxophone? If so, how?

Yes and no. You can play multiphonics, but it is not something that is easily described in a forum like this. Also, the multiphonics are not what people like to hear. It isn't like you can play a duet with yourself and make it sound pretty. There is a "saxophone" that does play two simultaneous notes called an aulochrome, but don't expect to afford one since I'd bet there are less than 10 in the world. Google aulochrome and there is even video of one playing.

it's not possible to play two notes at the same time on any instrument that you have to blow into. you would have to make a chord and that's impossible on anything besides like, piano and bells or string instruments. if you had two altos, you could.

It is very possible to play more than one note on a saxophone. Actually, you can even play four or more notes at once. This is part of what is called extended techniques and include for sax: altissimo, multiphonics(what you're asking about), growls, alternate fingering, harmonics, etc. This really isn't the right forum for someone to learn how to do this. You really should find a private teacher that can help. I don't know how long you have been playing, but if you haven't been experimenting with overtones and altissimo, then this might be too advance for you. If you want to give it a try, I can give you a pretty easy one to get out. Try fingering a low B, then lift either for right hand middle or index finger. Try both, different saxes work better with different fingerings. You have to adjust your throat a bit and a low E, middle octave D, and middle octave F# should sound at once. I was only able to get the E and D out for the first few days when I first tried. If you want to hear this, listen to Coltrane's live recordings from the sixties, he usually hits them at the peak of his solos. It can be a little hard to distinguish the difference between his multiphonics and altissimo though. If you listen to recordings of music by composer Christian Lauba or the 2nd movement of Sonata for Alto Saxophone by Edison Denisov. These are classical pieces and the multiphoncis are very easy to hear on them. You can find Lauba's stuff on Youtube. If you can't find a teacher to help you, here are a few books that can help:
Multiphonics for Saxophone by John Gross
Hello Mr. Sax! by Jean- Marie Londeix
SAXOLOGIE by Daniel Kientzy

Good Luck!!

You can play the saxophone and also hum a different note while playing, but this is not actually playing two notes at once

You can try what Rahassan Roland Kirk was famous for, simultaneously playing 2 woodwinds at the same time out of both sides of his mouth.

Amazing......

Good luck.

No, you can't play 2 notes at once, but there is a tecnique you can use:
Hum one note while playing the other.