YOU SAID:

i'm pretty sure i've seen this one before

INTO JAPANESE

私はこれを前に見たことがあると確信しています

BACK INTO ENGLISH

I'm sure I've seen this before.

INTO JAPANESE

確かに私は以前に彼を見かけたことがある。

BACK INTO ENGLISH

I am sure I have seen him before.

INTO JAPANESE

確かに私は彼を見かけたことがある。

BACK INTO ENGLISH

I am sure I have seen him before.