I encourage you to calculate how much of a difference in total keyspace this would make - and how long your attack will take even if these duplicates were removed.
Here is a value that might be helpful with your calculation.
This - (26+10)^12 - is how many guesses it will take to exhaust the keyspace.
Taking this number, and dividing it by hashes/second rate of your platform, should make it clear that your attack, even if you could cut the time in half (which would be much better than the keyspace reduction you're trying to do), will take a very very long time to run.
But I still encourage you to do the math for yourself, because it's hard to assimilate/believe until you do it yourself. Always do the math.
Here is a value that might be helpful with your calculation.
Code:
$ mp64 --combinations -1 ?u?d ?1?1?1?1?1?1?1?1?1?1?1?1
4738381338321616896This - (26+10)^12 - is how many guesses it will take to exhaust the keyspace.
Taking this number, and dividing it by hashes/second rate of your platform, should make it clear that your attack, even if you could cut the time in half (which would be much better than the keyspace reduction you're trying to do), will take a very very long time to run.
But I still encourage you to do the math for yourself, because it's hard to assimilate/believe until you do it yourself. Always do the math.
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