I took postinor-2 on sunday morning after having unprotected sex.. on tuesday i had another unprotected sex ..is it important for me to take again postinor-2 or i am safe??

You are probably safer to take it again even though there may be some residual protection. Since you may still get pregnant despite taking the medication, if your period is late it will be important to do a pregnancy test. Depending on this type of emergency contraception is not your best option, both in terms of effectiveness and for long term health.

There is not 100% "safety" involved from "unprotected sex" from taking "postinor-2". It will not create a problem by taking the postinor-2 again, but there may be light bleeding from withdrawal a day or so later. If your period is delayed, obtain a serum HCG test to be certain about pregnancy.