Plaintiffs, as limited by their briefs, appeal from so much of an order of the Civil Court of the City of New York, New York County (Margaret A. Chan, J.), entered August 15, 2011 as (1) denied their motion to amend the complaint to add a cause of action for breach of contract, and (2) denied the motion of plaintiff Stuart Levy for prejudgment interest on the prior award of $158,855.36.

Per Curiam.

Order (Margaret A. Chan, J.), entered August 15, 2011, insofar as appealed from, modified by granting the motion of plaintiff Stuart Levy for prejudgment interest on the award of $158,855.36 issued to him on the conversion cause of action and remanding the matter to Civil Court for calculation of such prejudgment interest; as modified, order affirmed, without costs.

Plaintiffs' motion to amend their complaint was properly denied, since the proposed new cause of action for breach of contract was duplicative of the extant legal malpractice claim (see Laruccia v Forchelli, Curto, Schwartz, Mineo, Carlino & Cohn, LLP, 295 AD2d 321 [2002], lv dismissed in part, denied in part 98 NY2d 753 [2002]; see also Fross, Zelnick, Lehrman & Zissu, P.C. v Geer, 120 AD3d 1157 [2014]).

With respect to the substantial ($158,855.36) award previously issued in favor of plaintiff Stuart Levy on the conversion (third) cause of action, said plaintiff demonstrated entitlement to prejudgment interest on that award (see CPLR 5001[a]; Zimmerman v Tarshis, 300 AD2d 477 [2002]; Mar Oil, S.A. v Morrissey, 982 F2d 830, 844-845 [2nd Cir 1993]). Contrary to defendants' contention, the conversion cause of action sounds in law, rather than equity (see Hunt v Hunt, 13 AD3d 1041, 1043 [2004]; Eighteen Holding Corp. v Drizin, 268 AD2d 371 [2000]). Nor is the law of the case doctrine - invoked by the motion court in denying prejudment interest - binding on this appellate court (see Martin v City of Cohoes, 37 NY2d 162, 165 [1975]). We remit the matter for a determination of the accrual date for such