[jugad]

They used the GCD (greatest common divisor) algo to find any common divisors between 2 large keys. 231 was such a number.

This signals to me that both the keys are corrupted/bad to have really small prime factors (3, 7 and 11).

I have taken courses on discrete math, cryptography and read a few prime generation algos. Its a standard first step to check numbers against primes upto a million or so (nowadays, a billion). No prime generation algo I can imagine generated these keys.