the codes are chosen to be low ambiguity -- they have low crosscorrelations over the time/frequency variations expected. In such cases, the patterns minimally effect each other. when codes are orthogonal, they should not interfere. in practice they might due to variations in time/frequency, as well as any non-idealities of the receiver.
eg, the codes +1, -1, +1, -1 and +1, -1, -1, +1 are orthogonal. if you have:
+A+B, -A-B, +A-B, -A+B transmitted, and do correlations against the two codes, you will get an amplitude of 4*A for the 1010 filter, and 4*B for the 1001 filter.