DTC P0141 & P0161 Codes 1997 GMC 5.7

I had my SES light pop on after driving a mile or so. There were no drivability issues so I preceded home 210 miles away with no issues.
I got into town and went to Advance Auto to get it scanned and had the
above codes DTC P0141 & P0161 O2 Sensor Heater Circuit Malfunction (bank 1 sensor 2 & bank 2 sensor 2). According to my wiring diagram they both get power with key on from eng 1 fuse. I checked the fuse and it was good and I was getting power to the fuse. I crawled under the truck and disconnected the closest plug and I was getting power to the sensor. The sensors got warm but not too warm as I could touch it without burning my hand.
Is it unusual for both to crap out at once? Will this cause me drivability issues such as mileage dropping? My mileage has sucked for a while 13.5-14.5 in town since I owned it. This is the first time I had that light come on since I owned it. My father has a 96 and his mileage is around 16 or so. Would these sensors be a player? I thought only the precat sensors controlled fuel flow? Thank you!
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Never heard of both crapping out at the same time, but Murphy is an a-hole, he he he. The post-cat sensors just monitor catalyst efficiency, and AFAIK they have little or nothing to do with fuel delivery.
Could just be a fluke. I'd clear the codes and see if they come back.
Doc
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