HOWEVER, I would strongly recommend you go for the 698 before the 697. The reason being is that the 698 will be accepted in lieu of the MD100. Essentially, if you run out of time for the 697 then all you have to do is take the MD101 and become certified on the new certification.
I think the new cert is Modern Desktop Administrator. "
So you probably would want to do the 698 first no matter what, and as far as voucher interchangeability, Microsoft may tell you.. I'm not sure.