The Anderson Power Products SB50 series connector (used by convention in FRC competition) is a sufficiently old design that compatible products from other suppliers are now available, of which the TE/Amp Power Series 50 is one.
Red 2-positions housings can be found here.
Contacts for 6 AWG wire can be found here.
Contacts for 10~12AWG wire can be found here.
Pre-packaged kits (1 housing + 2 contacts) are listed here.