Justin, maybe I am missing something in your description. But, I don't see how using a double-sided tape satisfies the 2-measurement process.
If you mis-anchor for one pass, say 1 foot short, both sides of the tape will still show you have enough length. So, you may measure what you think is 1,000', or 304.8 meters, but it is actually 999' or 304.45 meters. Appears that you have measured correctly, but without pulling the tape a second pass, you may make a mistake.
Same concept as me using both an electronic counter and a Jones counter at the same time, and riding a course once. Both counters say I rode the right distance, but if I made a wrong turn, or swung too wide, or cut a corner, it won't show - my course would be wrong.