Shopper's currently doubles all manufacturer's coupons to .99. So, if you have a .75 off coupon, they will double it to 1.50. A $1 coupon is redeemed for $1, unless they are having their special Dollar Doubler promos, where they double an unlimited number of $1 coupons.

Shopper's is currently stating "Please limit yourself to 4 identical coupons." ( I assume this is per transaction, since Shopper's has no club card, etc . )

Shopper's accepts IP's ( Internet coupons / Coupons printed from the Internet )

"We do accept internet coupons for CENTS OFF / NO FREE ITEM COUPONS:

SHOPPERS INTERNET COUPON POLICY

Shoppers Food & Pharmacy currently accepts CENTS-OFF internet
manufacturer coupons for up to $1.00 off. However, due to an increased
number of fraudulent internet manufacturer coupons in the marketplace,
Shoppers cannot accept internet coupons for FREE items. We realize that
many of these manufacturer coupons may appear to be legitimate, however,
most are fraudulent and are not honored by the manufacturer. We
apologize for any inconvenience and reserve the right to amend this
policy at any time."


From their website:

Internet Coupon Policy
SHOPPERS will accept valid manufacturers’ coupons obtained from the internet with a face-value up to $1.00. Internet coupons with a face value of $1.01 or above or FREE offers will not be accepted. Coupons must contain valid redemption information to be honored. SHOPPERS reserves the right to refuse any coupon deemed to be fraudulent and the right to change or terminate this policy at any time.

Double Coupon Policy
SHOPPERS will double the value of valid manufacturers’ coupons with a face-value of up to 99¢ (example: 25¢ = 50¢, 50¢ = $1.00, 75¢ = $1.50.) Valid manufacturers’ coupons with a face-value of $1.00 or greater will be redeemed at face-value only (example: $1.00 = $1.00, $1.50 = $1.50, $2.00 = $2.00.) Manufacturers’ coupons may be obtained from the newspaper, mailers or internet. Coupons must contain valid redemption information to be honored. We reserve the right to limit manufacturers’ coupons eligible for “doubling” purposes to four (4) identical coupons. Manufacturer’s coupons that state “Do Not Double” or “Not subject to Doubling” will be redeemed at face-value only. SHOPPERS reserves the right to refuse any coupon deemed to be fraudulent and the right to change or terminate this policy at any time.