TDC requires a certified copy of warrant before they will place a detainer.

They currently have the original warrant in their possession. They would would like to know if they, as the holder of the warrant, can certify a copy of it, even though the warrant didn't originate with them?

I've looked, but haven't found anything even toughing on this.

Court clerks routinely certify copies of documents in their possession that they did not create.

Certification is only a representation that the copy is a true and correct copy of the original document(s) and does NOT include any representation regarding the contents of the original (like a "verification" would). If TDC has the original, they can certify that a copy is a true and correct copy of the original document.