The Counterparts states that parties need not sign the same copy of an agreement and any of the copies can be treated as an original for evidentiary purposes.
Counterparts. This Agreement may be executed in counterparts, each of which shall be deemed to be an original, but all of which, taken together, shall constitute one and the same agreement.
When Counterparts Become Effective
This Agreement may be executed in counterparts, each of which shall be deemed to be an original but all of which taken together shall constitute one and the same agreement, and shall become effective when one or more counterparts have been signed by each of the parties and delivered to the other party.
Counterparts by Facsimilie
This Agreement may be executed in two or more counterparts, and by facsimile, all of which shall be considered one and the same agreement and shall become effective when one or more counterparts have been signed by each of the parties and delivered to the other party, it being understood that all parties need not sign the same counterpart.
Counterparts by Facsimilie or Email
This Agreement may be executed in two or more counterparts, each of which together shall be deemed an original, but all of which together shall constitute one and the same instrument. In the event that any signature is delivered by facsimile transmission or by e-mail delivery of a ".pdf" format data file, such signature shall create a valid and binding obligation of the party executing (or on whose behalf such signature is executed) with the same force and effect as if such facsimile or ".pdf" signature page were an original thereof.
No Limit to Counterparts
This Agreement may be executed in any number of counterparts, each of which when so executed and delivered shall be an original hereof, and it shall not be necessary in making proof of this Agreement to produce or account for more than one counterpart hereof.
The clause permits the agreement to be executed in multiple, identical, copies, when, for example, the parties do not sign the document in the same location. However, it does require that the documents are identical; and arguably the execution of a signature page does not constitute an agreement between the parties.
There are two main rationales for the clause. "The first is that the counterpart clause 'makes it clear that each party need not sign the same copy of the document in order to have a legally enforceable agreement.'"
The second rationale, taken from The American Bar Foundation's Commentaries on the Model Debt Indenture Provisions states (p 590) which states that "it is highly desirable to include a provision relating to counterparts in order to avoid any problem as to which of the several signed copies of the Indenture is the original."
Hereof, Thereof, and Everywhereof: A Contrarian Guide to Legal Drafting by Howard Darmstadter. Copyright 2002 by the American Bar Association.