I have two lines as well. They are not really separate since I think we all time them together. Ever have the mainsheet slip off the back of the boat? I have had it go off the back and around the rudder. I have learned the simplest and fastest thing to do is untie the traveler line from the mainsheet, pull the mainsheet back on board and retie. Takes about as long as it took to read that description. Another reason is that it makes taking you mainsheet blocks off the boat really easy. You don't have to undue the split tail end of the traveler line which is a PIA to tie back correctly. During transport the traveler line can then be used to tie stuff down.