First off: while, technically, I am being asked to do "the work of two people", it is worth noting that only one of the two people (ie, me) has been working full-time. I work, oh, 180 hours a month, let's call it. The person I am replacing works 40-60 per month. No one is asking me to do 360 hours' worth of work in 180 hours.
Second: The person whose job I am taking over does not work very efficiently and is highly resistant to changing his methods to do it faster. Neither I nor Glinda consider it impossible to do his job in, oh, 20-30 hours a month, once I've had time to figure out what needs to get done and how to do it better.
Third: Prior to this shuffling, I hadn't had a full workload for a few months. That is, I was spending a fair bit of time taking online courses, reading the Wall Street Journal, and doing other not-very-work-like activities while I was on the job. Glinda would shuffle projects to me and I'd be busy with those in my extra time, for a while, but when between projects, things were pretty slow. So it's not like I had a full 180 hours' worth of work to do before and will always need to put in overtime in order to do anything extra. Ultimately, I ought to be able to absorb the additional work into my routine. Glinda specifically asked me if I was willing to do this, and I agreed.
Fourth: No one at my job is bullying me. There is no "do this work or we'll fire you!" There's no yelling or screaming. There's no "what do you mean you can't get it done in this timeframe, you lazy goof?" My job stresses me because I think I should be getting stuff done, much more than any external stimulus. Yes, Glinda does have a somewhat irritating habit of giving me several large projects to do at once and then asking me "So, how are they going?" But it's not as though she accuses me of incompetence or slacking or offers any kind of admonishment, really, when I tell her "They're not, because I'm doing this other thing that you gave top priority to first."
Fifth: I did get a raise out of the new job duties. In fact, I got it back in April, as soon as I'd received some training on how to do it. I am being compensated for saving the bank labor costs.
I expect my current woes to be temporary. Things are bound to improve once I've had a chance to settle in. It's especially bad now because not only did I just get back from vacation (so stuff has been piling up) but several unusual problems/projects have hit all at once. (Typically I only have one or two odd problems on my desk, instead of a whole stack).
To sum up: in the long run, it ain't that bad. It's just this current sprint that hurts. ;)