Filters filter better to a point the longer you use them. So a filter used twice is actually keeping your oil marginally cleaner.
On a non-sludged engine, most filters have so much filtering capacity they could be considered overkill.
The 4-6 ounces of oil that doesn't get changed is inconsequential, meaning your TBN will be a 1.9 instead of a 2.0 had you changed the filter. Whoopty doo.
I have been doing two changes per filter for 10 or 15 years and it is perfectly fine. I just try to use a better filter with better media and a silicone anti-drain back valve, for piece of mind. A decent filter can definitely handle it.