Is it possible to have eustachian tube dysfunction effect both ears at around the same time?

Yes: Eustachian tube dysfunction refers to inflammation/clogging of drainage tube that connects middle ear to back of throat, normally allowing one to equalize pressure but if not functioning properly, leads to abnl pressure, muffled hearing & pain. Check out http://goo.gl/N6JX6M. There's no reason that both ears can't be affected at same time.