Merchant seaman's tickets

[LizzieL]

Was it possible for the same man to have two tickets with different numbers?

FindMyPast has records for two William Elthams.

Register no 256,883
William Eltham
born at St Georges East, Middx
March 1823 (no day included)
capacity Seaman
Height 5ft 9 ins  Hair sandy
complexion ruddy   eyes blue
marks none
first went to sea as a boy in 1835
issued at Liverpool 30 Jun 1835

then the second record
276,667
William Eltham
born London Middlesex 18 Jun 1822
capacity seaman
Height 5ft 9 ins  Hair sandy
complexion fresh   eyes blue
marks W.E on left arm, scar under rt eye
first went to sea as a boy in 1835
issued at Liverpool 12 Nov 1845

Both can write and neither has been in the navy or foreign service.

The height (which seems tall for that time) is the same, so are eyes and hair. Complexion might be a bit subjective and the marks could be acquired between Jun and November 1845.
I can only find one William Eltham born around the right time which would fit.

Son of William and Clara born 19 March 1825. not baptised until 1834. That might not be accurate, seeing that they had waited so long to have him baptised. 
This William is also the only one I can find on any census.

[seaweed]

Simple answer. Yes.
The ticketing system was widely unpopular with mariners and was treated with contempt. The records on FindMyPast are office copies. Seaman were given original tickets, size approx 7 1/2 inches by 4 1/2 inches. He was supposed to carry it when at sea and was given a small metal box, which was attached to his belt into which by folding the ticket into eight, the original was kept. So, many were lost, destroyed either by the elements or by deliberation.