We demonstrated the synchronization of offset and repetition frequency between two independent Yb-doped fiber mode-locked lasers by injection locking. By injecting master-laser pulse-train into slave laser cavity, stability and accuracy of master frequency comb are transferred to slave comb. Passive stabilization of frequency comb offers robust and convenient way to duplicate frequency comb that can be applied to long-distance comb transfer. Injecting master pulse would also help to initiate and stabilize mode-locking of high repetition rate or ultrabroadband frequency combs. Additionally, we also demonstrated even more robust synchronization of combs can be achieved with the help of active stabilization of relative offset frequency difference.