It's silly calling this a speedball. It shares very little in common with a coke/dope shot. No bellringer, most importantly. And the best thing about mixing heroin and coke(besides the rush) is the heroin covers up the coke comedown, with meth that's not going to happen as meth lasts longer.
But to answer you question, I can't see any benefit to poking yourself twice. But you might as well not even do but enough heroin to keep yourself out of WD, save it for when you are coming down hours later. You won't even feel the heroin when on a proper dose of meth.
I don't know why people are always trying to call any stimulant/opiate combo a speedball, I guess they just haven't tried the real thing. There really is very little in common with any of the other combos to a true speedball, you might as well just evaluate the combo independently of cocaine.
edit: Guess I should throw in a word of warning for HR, since I talk so nonchalantly about IV abuse of these compounds I worry people will interpret that as condoning such behavior or not understand the risks and dangers inherent in habitual use. If you haven't done a speedball before please don't, in fact stay away from opiates if not already dependant, and never IV cocaine under any circumstances. IV cocaine is just too fucking hedonistic, easily the most overwhelming singular experience I have ever tried, and so compulsive you will more than likely cause serious self harm trying to cram more and more into your veins well after you should have stopped. Even now, when I have ruined my life with opiates over and over again, and have been on buprenorphine for some time, I do still look back on them with some nostalgia and if I could have an endless supply without any financial burden I would do it in a heartbeat, even now the only thing that stops me from getting on methadone are daily clinic visits. But IV cocaine is different...it scares me, and when I think back on it the only thing I feel is shame; not because of any wrong I did to obtain it or any harm it caused someone around me, I never devoted myself to cocaine the way I did opiates, just the feeling it gives you, people aren't supposed to experience things like that. And its amplified by the fact that even then I knew I was doing my health serious harm with the act and was gaining nothing positive out of it, like I can convince myself I am with opiates. I imagine its a similar emotion that people who had some portion of their life consumed by a deep dark sexual fetish, but have broken free from its grip, feel.
