A whipstock assembly is provided for lowering within a cased wellbore, cutting a window through a casing for drilling a sidetrack borehole, and retrieving with conventional fishing tools. The whipstock assembly includes two separate whipstocks having different tapers, and which are releasibly coupled for separately retrieving from the cased wellbore. A barrier member is provided to prevent a tapered face of one of the whipstocks from wedging debris between the whipstock and the casing.
