TC17:

Using a single face clamp for carrying more than one roll (I'm assuming paper roll) simultaneously is considered an unsafe condition. One factor that determines lifting capacity of the paper roll clamp is the friction surface area of the clamp. Splitting the single clamp face between two rolls reduces the friction surface area per roll. This reduction could lead to a load slipping through the clamps with potential for damage/injury/death.

Split clamps should be used for carrying additional rolls. Each roll should have a clamp face fully engaged on the roll. The weight of the roll must not exceed the rated lifting capacity of the clamp attached to it. The total weight of the rolls being lifted cannot exceed the rated lifting capacity of the truck with attachment(s).

Many factors enter into recommended clamp placement. An excellent source of information are the Operator Guides published by Cascade (Cascorp) for their paper roll clamps (especially the Safety Rule and Roll Handling Basics sections of the guides).

Google: Cascade Corporation International (or) Cascorp;
Click on Cascade Corporation International Americas;
Click on Paper Roll Clamps;
Click on Support;
Click on Search Parts and Service Manuals;
Using middle search box, specify Product Family (Paper Roll Clamps) and specify Document Type (Operator Guide);
Click on and review selected paper roll clamp documents.

(Safety information on other Cascade/Cascorp attachments can also be found in a similar manner.)

Safety information can also be found in the User Manuals published by Bolzoni Auramo for their Paper Roll Clamps.

Google: Bolzoni Auramo;
Click on Lift Truck attachments, Lift Tables;
Click on Download;
Click on Paper roll clamps;
Click on and review selected paper roll clamps documents.

(Safety information on other Bolzoni Auramo attachments can also be found in a similar manner.)