load on beam

huangyhg

load on beam
i built a rectangular pergola, (14'w x 3'd x 7'h,) framed by four 6x6 posts, anchoring one end of a 1200 sq ft (30'w x 40'l) trex deck. i plan to install a 5-ft wide wooden swing or two hammock chairs, attached to one of the two 4"x6" 14-ft wide cross-beams.
questions:
1. will the horizontal 4"x6" pressuretreated cross-beam,supported on 14-ft span points by 6x6 posts, be able to support the weight that the swing or the hammock chairs, plus people, maxing at 600 lbs?
2.  if not, will another 4"x6" pt cross-beam piggy-backed on top of the existing 4"x6" beam, be sufficient reinforcement to be able to support the said load.  
the answer/s to the above will also be applied to the triangular pergola on the other end of the deck.
thanks in advance for your help.
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