We　study　the　entanglement　dynamics　for　two　coupled　multi-excitation　cavity　fields,　each　independently　interacting　with　a　two-level　atom.　We　find　that　even　when　the　atom-field　system　is　initially　not　entangled,　the　fields　can　become　heavily　entangled　through　postselecting　of　the　atomic　state.　The　field　entanglement　entropy　is　dependent　on　the　total　excitation　number　but　independent　of　the　coherent　photon　hopping　strength.