RTS (end of the routine, new one starting) + LDA $DD00 + ORA #$10

$DD00 is a hardware register, where one typically set/unset/read individual bits.
Having a set of trivial helper subroutines to set/clear individual bits (or groups of bits) is an obvious solution (thus not copyrightable), some similarities are unevitable.
Besides, in this case (since the similarity does not even cover a single subroutine from start to end) it is clear that the similar code actually performs slightly different actions.