Doc,
beware that the Roland G-70 uses the "Intelligent" mode as the default chord recognition mode (intelligent means that it takes just one finger to trigger a chord); so, unless you specifically switched to pianist mode, my guess is that you were playing with the intelligent mode on...
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Korg Kronos 61 and PA3X-Pro76, Roland G-70, BK7-m and Integra 7, Casio PX-5S, Fender Stratocaster with Fralin pickups, Fender Stratocaster with Kinman pickups, vintage Gibson SG standard.