Is dual mining possible on the low range graphic cards like gtx 1060, 1070, 1080 and 1660s? I've tried dual mining only on RTX series not GTX, and if Dual mining can be more profitable to the RTX3 series why not the smaller graphics cards?.
It is possible and the best option is to dual mine with Zilliqa as that is not going to burden your cards that much because with Zilliqa you mine such coin for 1.5 minutes or 1 minutes every hour and then you continue to mine normally only the primary coin.Other algorithms are heavier than Zilliqa but let me remind you of people being extremely rich now the ones who dual mined Decreed in 2016 and kept those,a coin which was 250 USD exactly one year before now and it is now 65 USD,back then it was less than 1 dollar and not that difficult to mine with the RX 470 Gtx 10 series.
In the end dual mining is only a gamble,I miss not to have dual mined decreed back then.