Well, I'll jump in but I am not a mechanic and this would be purely a guess.

The chances of both motors going out at the same time in a possibility, but
probably not.  One motor going out and causing the other to go out could be
a realistic possibility since you said one went out just after the other.
They are both the same age and have been exposed to the same conditions.

Another thought would be something limiting the current.  First, of course,
would be the fuse (#26 a 20 amp).  If one motor had shorted or something, it
might have caused it to go out.  You might see other indications of this,
check your owner's manual for common items or just check the fuse.

Have you noticed any other electrical problems like dim lights or buzzers
that don't really buzz?  The battery in my truck just went out and yours may
be getting weak.  If not weak, possibly bad connections limiting the current
from corrosion or bad grounding.  As someone mentioned, corrosion in
electrical connectors can limit current flow.  If you have the RAP module
(Remote Anti-theft Personality), it is common to both doors.

Does it make any difference how much electrical load is on the vehicle when
you work the locks?

Does it make any difference whether you are locking or unlocking the doors?

Do you remember the switches getting wet lately from a rain shower or
something?

If it was me, I would start with the fuse and then move to the Switch
(drivers side) or motor, whichever is easier to access, and check for
corrosion and voltage, and freedom of motor movement.  Some oil or other
lubricant in a motor that is binding may release it.

Clark