The FDCPA does refer to a DV request as a "dispute of the debt, in whole or in part," but it is a different animal of dispute that one made under the FCRA.
Unlike the FCRA, which requires one to assert a specific inaccuracy in credit reporting, and provide sufficient documenttion to permit an investigation of its accuracy, a DV request does not require anything more that a request for valdidation. However, also unlike a dispute under the FCRA, a DV request under the FDCPA imposes no period for or requiement to verify. If sent within 30 days fo dunning notice, its efffect is to impose a cease collection bar on the debt collector, which remains in effect until such time as the debt collector provides the requested validaation. They can choose never to respond, and simply accept a bar against continued collection activities.
If you send a timely DV, the cease collection bar prevents the debt collector from continued collection activities, which includes any response by negotiatio of terms of payment, such as reply to a PFD offer.
If you choose not to pay a debt for which you are unsure that you owe, then it is most likely prudent to send the DV,but recognize that they have no requirement to respond, and it places any negotiations on payment in limbo.
If you wish to simply attempt to get the collection deleted and thus pay a debt that may not be yours, then you can offer the PFD and forgo the DV.
If it has been more than 30 days since they sent dunning notice, then your DV imposes no cease collection bar, so you could send the DV and also make a PFD offer.
Howver, they could continue collection activites as normal, and ignore both requests.
