if i married a Polish girl in Poland then she would have an altered version of my second name?
only if you have a typical Polish surname ending in -ski, -cki, -dzki, and even then she would rather have a choice, because it would complicate her life abroad, and with you being a foreign citizen, I guess the rules would allow her to receive your surname in an unaltered form.
Generally (for official purposes) only the surnames ending in -ski/-ska and -cki/-cka and -dzki/-dzka (in total about 35% of Polish surnames) have different forms for males females.
Surnames like (I mention only top 20 entries from the most popular Polish surnames list, but the rule is the same) Nowak, Wójcik, Woźniak, Mazur, Krawczyk, Kaczmarek have only 1 form, no matter what sex is the person.
A more complicated situation exists with surnames that are adjectives (addjective in Polish normally have different forms for each gender), some of them them are used in both (m/f) forms, some (it's probably a newer trend) only in the base (masculin) form, it's probably
up to the person who carries such surname to decide what version she wants in her documents, but I'm not sure (I don't know the laws in that matter).
Biały/Biała (= White)
Czarny/Czarna (= Black)
Historically most (maybe all) surnames existed in feminine forms, for example:
Nowak - Nowakowa (wife) - Nowakówna (daughter).
You can find them even in the writings from before WWII.
Today, these forms are still in use in everyday language (the "daughter form" mostly by older people), but not for official purposes.