condo fees an liabilty

I live in a condo complex and pay association dues. I have a receipt showing that I paid the dues for the month of September. The property manager lost my check and wants me to repay for the month of September, as I have a receipt showing that I paid the dues, do I have to pay them again? Also, there is a common area for use by the complex, he informed me that my son can not have friends over to use the common area as it is a liability. I have insurance on the condo that has a clause stating that anyone who enters my home is covered in case of an accident. This valid, r do I needt to take out another kind of insurance? Also if my son is not allowed to have friends over to use the common area, shouldn't everyone with access to that area be informed of this.
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