The cost of one key was probably so close to the price of two that its worth the security of just getting it done. I would expect $50 of your cost to be labor, regardless of number of keys. Don't worry about it too much .
It can also be difficult to get keys cut without a programming as some places don't want to separate the labor. When I have ebay-bought keys (car or those pesky "do not duplicate" keys), I go to Home depot and buy a non-chipped car key or house key, have it cut, then ask them nicely to cut the other key and reassure them I won't try to return it if it doesn't work. I get away with it 75% of the time. Worse case scenario, you spend $2.50 on an entry only key
I had a ~22 year old kid get into a tizzy and tell me if the key is wrong, it'll set off my alarm, lockout the car, and other nonsense and that I would need to come back the next day to buy am official key. He didn't even cut me a chipless key becaus my key had a chip and turned on the light in the chip checker. Oy.