Yes, you should create two listings both for sanity and legal reasons. Making two separate listings allows Airbnb to send your mom's payments to her and your payments to you which saves you both income tax headaches and could resolve any potential disputes about money. Supplies and expenses for each house can more easily be divied when the homes are operated as separate businesses. It also allows separation of business for liability purposes too. A bad review for you will not hurt your mom and vice versa.
As for your own listing's star rating- it won't affect it. But if someone looks at your profile they will see the second listing as well as a link to reviews on other properties, so the two accounts are somewhat connected and can affect each other.
The only advantage is that when starting a new home it does give you some good reviews already in your portolio, even if they are for a different listing.
Best of luck!