[amsat-bb] dual band vhf/uhf antenna

I built the combination dual band 2meter/70cm antenna found at WA5VJB's webpages. I chose the 5 elements on UHF forward and 2 elements on VHF rear. All elements are in the same plane. I now read elsewhere that in-same-plane uhf/vhf elements can interfere with each other. I visited the Arrow website and see their LEO antennas are opposing for uhf/vhf. My question is if i made a mistake building the uni-plane version? Why did WA5VJB has such success?