I'm not sure these sentence are correct.
ACTRANSFER has problem on 1 May at night and then fixed that on 2 May at night so It might be send files again on 2 May due to duplicate files.

Question

Answer

Some mistakes about tense, you said has problem.then fixed, it mixed.
"ACTRANSFER had a problem on 1 May at night and  fixed it on 2 May at night so It might be send files again on 2 May due to duplicate files."

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