It depends on whether or not you already have enough speaker cable to do so. If you do not then I would say don't spend your money on extra lengths of cable, spend it on music.
Whilst many companies do indeed make their speakers with 2 (or more) sets of binding posts it is, in my experience, not worth employing them to bi-wire fom one set of speaker cables on your amp.
If, however, you can bi-amp then this is a whole new ballgame and it is, in my opinion, why most manufacturers employ multiple binding posts.
You will find that even some rather expensive speakers on the market today only have one set of binding posts as some manufacturers believe little can be gained by spending extra cash on expensive binding posts and so use this money to put better quality components into the cross-overs or to keep costs down overall. The speakers I use are like this even though they have 3 drivers per box.