Or either or neither? That's fine too.
With the 2009 (at last!) remastered reissues of the entire Beatles catalog, I'm dutifully listening to each and every one, including the mono versions. I'm not going about it in an organized or sequential way, but instead listening as they arrive: by mail from Amazon, in person from Starbucks or the local library, or from my friend Nick (thanks Nick!), so I'm not doing that "evaluate the artists' growth from hopped-up Hamburg-happenin' urchins to world weary studio warriors who had to 'let it be' an eventful seven years later" thing. Not today, anyway. I'm just going to talk briefly about the issue of mono vs. stereo, their first album Please Please Me in particular.
As the reissue liner notes point out, mono was the preferred format in the early to mid 60's, and stereo records were released only in small numbers for hi-fi listeners. They recorded the whole album in one day (!) to only two tracks, so when creating the stereo mix, all the voices went on the right side and all the instruments went on the left. Listening to this "fake stereo" mix now, I notice quite a bit of bleed-through of each to the other side. If it weren't for that, it would sound really weird. I mean, how does a band of four guys singing and playing guitars simultaneously somehow put their voices on one side of you and their instruments on the other? Not physically possible.
So the official release, and reissue, of this album really should be the mono version, where you hear all the instruments and voices in one big mash on all sides of your ears, which is what you would've heard if you'd seen them from the back of Liverpool's Cavern Club in 1962 anyway. (Or more likely, out of one little speaker in your car.) But the mono version is only available with the box set (all you need is cash...it's pricey), and that's a shame, because most people will only hear this "stereo" version.
Someday, I hope a studio wizard isolates each voice and instrument and creates a truer stereo mix, putting John, Paul, George and Ringo in different places in your headphones, so you can close your eyes and imagine them playing here, there, but not everywhere.