This is not a Polish variant of
Paula. Polish etymological sources say that there is a confusion between the two names because the name
Paula is pronounced like Pola in some Polish accents(although in my accent they are quite different). Pola was previously only a nickname for Apolonia(Polish form has on e P) but is now used as an independent name. I know a sibset in Poland of Pola and
Ninel.
There is also the similar Polish name Poliana/Polianna. It is not related to the literary name Polyanna. It is the feminine form of the name Polian which is in turn the Polish form of the
Roman name Polianus.