I have noticed this as well Janet (about the first two leaves not always being representative of the leaves to come) and do not rely on them. I have noticed this with passiflora first true leaves starting out ovate and gradually becoming a combination of ovate and lobed leaves. I also wonder with all the wild Ipomoea around here if there couldn't be some cross-breeding? Does this happen? After all this seed did not come out of a nicely controlled seed packet but most likely from a bird's dropping, making it wild and maybe not so reliable. I really should have kept that seedling and grown it for awhile...i was just too hasty. Next time something interesting pops up, i'll grow it at least long enough to make a reliable ID. I am not sure we are going to be able to come to a certain conclusion from this one photo about the identity of this seedling, but i do appreciate your input. Now i know it wasn't a Jacquemontia and i'm feeling a lot happier about that.

Maybe another will grow Beverly, and yes there is a possibility a cross has occurred. I think Ipomoea cross fairly readily, those who want to keep pure varieties have to bag them to stop cross pollination. Correct me if I'm wrong!

I also think it's impossible to say for sure what this one is, I seem to recall those who specialise in Ipomoea mentioning variability.

Thankfully, you won't have to beat yourself up for pulling one you know you wanted.