Not an allene, but a conjugated system. Not absolutely sure about the mechanism, however, the instead of forming the unstable allene it will probably be rearranged to the conjugated alkene one way or another.
Polly, try working out the steps for yourself. At first the bromine diatomic is added to the double bond. With the first elimination is a return to the 2 alkene (3 bromo). However, the terminal carbon has become more acidic and through an elimination reaction with a base the end hydrogen will be pulled off and the double bond will form there. Depending on the reaction conditions E1 or E2 will take place. However I am thinking it is more of an E2; a strong base will be needed for E1 since a carbocation is formed. Nevertheless the allene is relatively unstable and I presume that it will rearrange through some means to the more stable conjugated system, 1,3 diene.