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Is implantation bleeding more common with a twin pregnancy? - pregnancy and bleeding more condition_symptoms

I suppose that I ovulate on both sides, 21 November and had sex on that day, because we are TTC. But today, 4 days of December, we begin to bleed. I had no common PMS symptoms like bloating. I have two children, both singles and never implantation bleeding? This could be an initial period (which was a cycle of 26 days) or it can be implantation bleeding?