To increase the likelihood that a double or cluster will not remain after the transfer, according to a further aspect of the invention, each progressive conveyor can be set at an angle in the horizontal plane relative to the one preceding it, such as a right angle as shown in FIG. 14, or an angle in the range of from 5-90 degrees, especially 10-70 degrees, as shown in FIGS. 15A to 15D. Following t