Where these done with a harmonizer?
They sound a little odd.

Personally i wouldn't use them, bought a lot of choir samples in the past once for a film-scoring job sounding quite better ... One of IMO more recent recommendable favs would be realivox 'The Ladies' -F

Being they're RTs they should be REAL singers. Are they?

Yes, they are Real Singers, e.g.
RT3069: Multi[Whole Song] VocalOohs Pop3ptMaleHigh1 85, VocalOohs Pop3ptFemale1 85, , David Wise and Shelly Justice

They are also listed on the PG Music Web pages with the Artist names.

I'm thinking the same thing because I tried creating a song with them, so I'll have to end up replacing them because of it. Here's how I used it.
https://soundcloud.com/dirtbom/it-really-dont-matter

Using them is like other RT's. It depends on the song and how you edit and put together the track(s). Also the tempo and key, where you want ooo and where ahh, etc. When you get them right they are sweet.

I'm using them in a new song that I'm still finishing up. I'll be posting it sooner or later. I think they sound great on it.

Sundance long time.
They just sound off. Sort of like one Real person signing through a harmonizer.
I'll check it out more.
I tried a typical 1-6-2-5 doowop.

Yeah, I sort of assumed because they're WMA files, but definitely using a harmonizer.