Yes. You can but be sure to increase the diameter of the tubing or the friction will produce a lot of heat losses. Similar to when you run two water pumps into one common pipe (or head).
You’ll get a slight reduction (in your particular case with an air pump, but a very large reduction in flow if you did this with a water pump and didn’t increase the head diameter)in output if you don’t increase the common head diameter.
Online redundancy has the caveat of friction losses.
If you see a dramatic reduction in output (test the before and after lpm of each pump with a large electrical tape sealed black heavy duty garbage bag if it’s a large pump or a large balloon for a smaller pump, or buy a $13 acrylic air flow meter of the appropriate lpm range ) than you’re putting too much back pressure on the bellows of the air pump and you will need to change out your air pump diaphragm sooner.
If you put a lot of back pressure on the bellows air pump you would be able to determine that from an ammeter test of the pump before and after the redundant pump set-up. With pumps of this small size the ammeter test won’t work to show small increases in back pressure.
I’m assuming that you’re attempting to have redundancy in the event of a blower failure? Or maybe just trying to increase air output?
Also, make sure you use LLDPE instead of soft vinyl or silicone tubing if you do decide to put the 2 air pumps on one common head. The harder and smoother plastic will reduce friction significantly. If your airlines transfer too much heat. If you see they don’t , than don’t bother.