"do at the same time" is a correct and usable phrase in written English.
It means to perform two or more actions simultaneously. You can use this phrase in a sentence when talking about multitasking or coordinating tasks. Example: I have to do homework, cook dinner, and help my kids with their homework at the same time. It's a lot to manage, but I'll do my best.
"This, I think, was a case of staff having too much to do at the same time".
But what are poor people in Bangladesh going to do?" At the same time, bucking conservative orthodoxy carried obvious risks, as Romney knew better than anyone.
While brushing my teeth, I would wander out of the bathroom in search of something else to do at the same time.
The idea was to take the best elements of going to see a live band but also to give people something creative and rewarding to do at the same time".
With several weeks between shows, we announce what matches will be on them gradually (one per week) so the fans talk about them and look forward to each announcement, which we tend to always do at the same time on a Monday.
Perhaps they will one day merge into an über-Zach and conquer the world of humor from all sides: in print, in film, online, and of course, in live performance: Kanin plays the harmonica, Galifianakis plays the piano, two things über-Zach could obviously do at the same time, with a little help from a harmonica neck-strap, which I think would really complete their/his look.
Internet users clicked on ads 18% more than they did at the same time last year.
It is just another simple blood test that could be done at the same time.
It was much different than my teammate did at the same time".
But the scan and the treatment cannot usually be done at the same time, because they interfere with each other.
"Showing everything done at the same time is antichronological in a sense," because there is no time passing, no progress.
