The ebay listing (ending June 23, 2004-not my listing) says this is a 27 inch high Conn tuba with an 11 inch bell. It looks like it is supposed to have a small, second bell and is probably a euphonium. Double-bell tubas were discussed here recently.
I'm curious as to what the horn really is.
Dean E
[S]tudy politics and war, that our sons may have liberty to study mathematics and philosophy. Our sons ought to study mathematics and philosophy . . . in order to give their children a right to study painting, poetry [and] music. . . . John Adams (1780)
I would say that the majority of double bell euphoniums that I have seen have been 4 valved (3 plus 1 change valve) rather than 5 valved. The last valve is always the switch valve, so in this case you are correct, it is a 3 valve horn with a bell change valve. I have also seen many of these where the small bell has been lost for any number of reasons. The smaller bell is predominately removeable, so it is easily lost. I'm sure that a good technician could make a second bell for this. I would think that an old, bell front, alto horn would be a good source for a bell that would fit.
The ebay listing (ending June 23, 2004-not my listing) says this is a 27 inch high Conn tuba with an 11 inch bell. It looks like it is supposed to have a small, second bell and is probably a euphonium. Double-bell tubas were discussed here recently. 
