Now that there is just one squence left in the sieve, it seems that sr2sieve is once again not selecting the best parameters automatically, so please try adding "Q 720" to the command line to see if it is faster. e.g. to sieve the range 500T501T:
sr2sieve zz i dual_s.abcd p 500e12 P 501e12 Q 720
I have only tried it on a 32bit machine so far, but it looks like sr2sieve version 1.8.11 with the "Q 720" option is about 95% as fast as sr1sieve would be. (I tested sr1sieve on the sequence 40291*2^n+1 to compare with sr2sieve on the sequence 2^n+40291).
It also looks like the sieving speed has almost doubled compared to sieving two sequences. I will do some more careful timings later.
