You could control it by use of Infused trait on one of your DW weapon which would then have 50% chance of proc vs normal chance. Remember there is status effects that might be useful in combination when put together and you can reduce targets resistance, weapon/spell damage or give yourself the same for a duration (5 sec). It depends on how you build and how your play your skills. DoT can trigger Valkyn Skoria as an example, direct damage can procs other sets etc that mighe be buffed or triggered by glyphs. If you only want a flat damage then you can use alchemy poison (and have glyphs as back up when those run empty on weapon). Disease damage (defile) is also useful for PvE for those times there are healers (adds) on a boss.
For one, glyphs don't have a 'chance' of proc. They proc as soon as they're eligible to proc (LA / HA / weapon ability) and off cooldown, unlike alchemical poisons. For another, the question was simple, about putting same glyphs on different weapons. It's not something to be done because glyphs of same type share same global cooldown. If poison on main hand proc'd, cooldown have started, and poison glyph from off hand won't be able to proc for same period either. Worse yet, if non-infused poison glyph proc'd, then normal, 4-second cooldown have started, and infused glyph (with halved cooldown) on another hand will not be able to proc for full 4 seconds either.