Generally, I imagine that anti-death-penalty voters will vote Yes on 66 and No on 62 and vice versa for pro-death-penalty voters. However, it's possible that a voter is simply motivated to clear death row by any means necessary because of all the extra costs it involves. Maintaining death row is expensive.
In that case, voting Yes on both makes sense. Either death row will get cleared out by getting rid of the death penalty or it will get cleared out by killing them faster. Either way, it's a cost savings. I find that logic to be cold and impersonal, but I imagine there are plenty of people who think that way.