seagate 160gb drive showing 2 extra 80gb partitions

hi there gaving a bit of a problem with my seagate drive its an ata drive and only really used for downloading too and storing stuff but recently and i cant remember what sequence of events triggered it it shows up another 2 partitons in disk manager so i thought it was an error so i made one of the partitons active and it popped up in my computer ! along with the original 160gb still working ?

ive not tried to read or write to the partition coz im too scared to incase it writes over any other data but what can cause this and how do i fix it ?