Yes Walmart Does Accept Manufacturer Coupons.
As long as the Manufacturer Coupons are not double the value or twice the value of the product coupons Walmart will accept them.
Walmart accepts Manufacturer Coupons that are printable and even soft drink caps and even Catalinas.
However while most Walmart Stores will not accept twice the Value Coupons I've found a few Walmart stores that consider them competitor coupons and will accept them so it's worth a try.