is it possible:
one jPlayer instance and 2 interfaces for it, at the same page.
Sample:

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As far as I can see (from looking at the source) it seems as though the events (play, pause etc.) are hard-wired to use the identifier of the interface “jp_interface_n”:
where n corresponds to the id of the player “jquery_jplayer_n”
So in the case above the player “jquery_jplayer_1” would infer an interface id of “jp_interface_1”.
I do not think what you are attempting to do is possible without modification of the jplayer component, although I have only looked at it for a couple of minutes so may have missed something.
You have two choices:
Ask someone who works on the project via the following Google Group:
jPlayer: HTML5 Audio & Video for jQuery
Create you own interface(s) and wire it up using their api:
jPlayer 2.0.0 Developer Guide