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6 duplicate page titles seems a relatively small amount. Duplicates are an issue in that search engines have to decide which page to rank. Applying the canonical link element can help with duplicate page titles sometimes, but if you are optimizing for different keywords on each page i do not think Google penalises heavily for this (I could be wrong) it just makes it harder for them to know which page to rank. If you are certain of the keywords you wish to rank for (and show this) throughout each page individually I do not think you should have a problem with your page titles.