These results make more sense for your father. I suspect the match is actually 12-12-12-14-14-14-14-14, making the only difference a 14>15 mutation. What the analyst sees are two peaks. Trying to distinguish between peak-height ratios of 5:3 and 4:2 would be difficult, given the normal variations.Click on the images here to see the variation in peak-heights:
However, the TMRCA ranges are so wide that it does not make much difference. With a 64/67 match there is a 95% chance that the common ancestor lived 6-19 generations ago, while a 63-67 match would give 7-22 generations ago.
Note that I made a mistake in assuming your father was R1b1a2. The DYS464X only separates alleles in this group, since they have c-types. Thus, the match could just order the regular DYS464 test from the advanced tests, if he wants a second opinion.