Yes and no....transfers can only go one direction each calendar year. So, if you transfer from contract A to contract B, then for the remainder of the year, you can only transfer OUT from A, and INTO B.
So, if you were to rent points (transferred) from a DVC member, you could only transfer them into B, not A for the remainder of the year.
There is no limit to the number of transfers you can do, but they all have to be in the same direction.
But, yes...one member with two separate membership numbers can transfer between those membership numbers.