This is not a collision, it is not the first time ever, nor is it in any way difficult to do. It is an inherent property of the secp256k1 curve that bitcoin uses. Taking the negation of any private key
modulo n is the same as negating the resulting public key across the x axis. As such, the two private keys which OP has given, which are modular negations of each other, produce public keys with the same x coordinate but different y coordinates.
Here's another pair:
0000000000000000000000000000000000000000000000000000000000000002
FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD036413F
which give the following two public keys:
04
c6047f9441ed7d6d3045406e95c07cd85c778e4b8cef3ca7abac09b95c709ee51ae168fea63dc339a3c58419466ceaeef7f632653266d0e1236431a950cfe52a
04
c6047f9441ed7d6d3045406e95c07cd85c778e4b8cef3ca7abac09b95c709ee5e51e970159c23cc65c3a7be6b99315110809cd9acd992f1edc9bce55af301705