We use the structure A就A,别B to indicate that a situation is not as critical as it seems. It is used to make sentences such as “if you forgot, it’s okay, don't worry”.
Instead of “A”, we should state two identical verbs or verbs with the object. Instead of “B”, we should state another verb or a verb phrase.
Examples
讲就讲,别用这个操纵我
Just tell me and don't manipulate me
jiǎng jiù jiǎng, bié yòng zhè ge cāozòng wǒ
走了就走了,别在意
He just left. But it’s not a big deal, and I don’t mind it
zǒu le jiù zǒu le, bié zàiyì
写错就写错,别想那么多
Even if you write it wrong, it’s not a big deal. Don’t worry