After I had a problem with using more than one manufacturer coupon I wrote an email to corporate and this was their reply:

Dear ExtraCare Card Member:

All earned ExtraBucks coupons associated with an ExtraCare card may now
be redeemed in a single transaction. The retail price must be greater
than the combined total of all coupons. Please keep in mind there is no
cash value back for any unused portion of the coupon.

NOTE: Use of Manufacturer coupons remains limited to one per item in
any transaction.

If you have any other questions please do not hesitate to contact us
either by e-mail or by calling (800) 746-7287. Thank you for taking the
time to contact us. I hope you have a nice day.
Sincerely,
Joseph Battey
CVS ExtraCare


I have attached in word pad this statement so you can print it off.