ECU P4120534 Super Stock / Pro Stock / Nascar

I was reading a thread the other day and some specs for a few ECU part numbers were posted as part of the discussion.

Years ago I bought a 4 pin ECU new in the box from a Chrysler dealer to carry in my car as a spare. Thinking that an ECU is an ECU.

After reading the specs in the thread I checked mine and discovered that I have been carrying around a P4120534. “Racing applications only to 10,500 rpm’s. Not for prolonged use under 2000 rpm.” What?

Anybody using one of these without any issues in a relatively mild street only car? I would assume likely not but what are the why nots?

Confused. Please advise if I should be buying a more appropriate ECU to carry as a spare.