The company is legit Judy, but there is no way to know if the check is.
Pay it into your bank. If anyone says it is a mistake, and can you refund the money via MoneyMart or Western Union, it is a scam, so ignore them and say you have contacted the bank and passed on all the details to them. Don't get into any conversations with them. In these days of smartphone banking, you can photograph the check top bank it and keep the original. You can then send it back if someone says it is a mistake :>)
There are scams that work like this. You get a check for some reason, you bank it. You are asked to pay most of it back minus an admin fee for your trouble. It seems like easy money for you. You pay them the money for the overpayment via Western Union. After one month, or even two months, the bank inform you either the account has been closed, or the check is fraudulent, a fake check. The bank take the money back, you are out of pocket for what you sent via Western Union, because with Western Union, there is no way to get the money back. They went into a Western Union shop, showed fake ID and walked away with your money.
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