How to apply partially applied receipt using Apply Receipt using automatch

Summary:

I have one invoice of 50$ and i have created one receipt of 80$ and applied the same receipt against the transaction using apply receipt automatch program. The receipt of 50$ amount applied successfully. Now, i created another transaction of 50$ and created new receipt of 20$ because i have already partially applied receipts available in the system against the same contract. Now when i re-run the apply Receipt automatch program system applied only 20$ receipt but not applied that partially applied receipt of 30$. So, why system does not applied that receipt.

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How to apply partially applied receipt using Apply Receipt using automatch