can we apply for an IPO from multiple accounts using the same upi for approving the mandate ?

Today, I tried applying for Unimech Aerospace using two different accounts with the same UPI. I received two mandates for approval. The first was approved, but the second one failed due to insufficient balance. I contacted Zerodha support, and they informed me that the same UPI cannot be used for two accounts. Is that correct? The reason for the insufficient balance is that I had applied for three IPOs (DAM, MML, and TLL), but none were allotted. For TLL, the amount has been refunded, but for the other two, it shows as unblocked, yet the amount is not reflected in my savings account. I thought I could still apply for an IPO even if the amount was on hold.