Sounds like Canadian Columbia got their artist credits mixed up on each side - on the U.S. release #38211 (originally released around 1 May 1948), the future bobby-soxers' idol was credited with the girls on "You Can't Be True, Dear," whilst they and they alone were credited on the yodeling flip.
Thanks for finding that out, mickey. I still had the page of the other site open, and it has a copyright notice of 2004, which is before Wikipedia existed to look up such obscure information.
I've just played this record, and the label information is wrong. Eddie Fisher does not sing on "Toolie Oolie Doolie," but he does sing on "You Can't Be True, Dear," where he is uncredited.
What I noticed is that "Toolie Oolie Doolie" has what must be some of the earliest electronic reverb effect in use on a record. The girls sing the title and other parts in yodeling fashion so as to sound like they're in the Alps. Every time it comes up, you can hear where the engineer pots down the dry channel and pots up the wet one, then back to no effect, on-the-fly. The singing is all done in one pass, no overdubs, so the engineer really had to be paying attention to get it right!
At the time this record was made, Eddie Fisher was still an unknown.
There is a website that documents recordings made by The Marlin Sisters between 1948 and 1951, but it says that there is otherwise little or nothing known about them now, including their first names.
"You Can't Be True Dear" made it into the Top 20 in sales during the summer of 1948, and "Toolie Oolie Doolie" reached #30.