I am 26yrs late to the game on this lol, but I was just listening to the different versions of "Sometimes" by Erasure that I have and I noticed a few things.
First of all, SOMEHOW I never noticed that the Single Version released in 1986 is a different mix than the one included on the album "The Circus" in 1987! The album version is actually a much cleaner and crisper sounding mix with less reverberation. How have I missed this all these years?!? The Single Version is used on all of their "best of" compilations and on the Erasure Singles Box Set, so I guess I got so used to hearing the Single Version more than the album version and didn't pay much attention.
The Album Version is also in a completely different key than the Single Version! Although, after listening closely, it sounds to me like the master tape for the Album Version was just sped up slightly to increase the tempo and raise the overall pitch. The length of both versions is generally the same but if you listen closely you will notice the Single Version fades out sooner than the Album Version. I tend to believe the tempo & pitch of the Single Version is more accurate because it is in the same key as their live performances.
After some discogs research, I see that the 7" record sleeve for the UK release of "Sometimes" says: "Mixed by Flood and Mike Pela". There is no mention of Mike Pela on "The Circus" packaging, so I wonder if the Album Version is just a Flood mix.
So why was the album version sped up?
The Extended Mix (aka 12" Mix) bonus track on "The Circus" CD's and on the CD-Singles is in the same key as the Single Version, except on the Erasure Singles Box Set, where the Extended Mix is ALSO sped/pitched up even more than the Album Version! What the...?