"would duplicate" is a correct and usable phrase in written English.
You can use it to refer to an action that is similar to something already done or existing. For example: "We can't do that, it would duplicate the effort we made last week."
F.B.I. officials believe such functions would duplicate what the bureau already does, the official said.
For many consumers, the $36 noted above would duplicate taxes already paid for a local telephone line.
The latter proposal aroused misgivings in Washington for fear that it would duplicate NATO institutions and damage trans-Atlantic cooperation.
But some of Mr. Bush's advisers worry that a European force would duplicate existing efforts and drain resources from NATO.
Like other resellers, Mr. Ostrowski was hoping the iPhone demand would duplicate the Xbox, PlayStation and Wii crazes.
The Council Speaker, Peter F. Vallone, has contended that the office would duplicate work done by existing agencies.
Whatever lines Leigh (and excited volunteers) traced on a desk, the quadrocopter would duplicate with an attached black marker on a whiteboard a few yards away.
Receive no financial assistance from other sources that would duplicate SDP assistance (scholarships, grants, and departmental funds may augment but not duplicate SDP assistance).
Who would duplicate a monument that had already been attacked twice, and expect tenants to move into the world's largest bull's eye?
He won control of all new international channels, preventing Warner Bros. from spending millions to build a staff that would duplicate Turner Broadcasting's.
In the AGM notice, Sports Direct's board said a new investigation would duplicate its existing review and be an unnecessary distraction.
