Ah, the old "Noah's Ark" grid. Certainly there's never been a race where the whole grid lined up two-by-two (unless you count Indianapolis 2005, which really shouldn't count).
I've had a quick look back through the records. When you go back before about 1980 things get a bit tricky with multiple-car and single-car teams; additionally in the 1960s and earlier, grids didn't necessarily line up two-by-two, but four-three, three-four, three-two-three and so on.
In terms of the most number of rows of the grid that had cars from the same, two-car team, the highest I can find is two examples with six:
Alternatively, if you start from the front row looking at successive rows, I don't think there has ever been a race where the top ten all lined up in pairs. I can find three examples where the top four rows were paired, plus one other row further back:
There have been some very close calls, though. If not for Brundle and Alesi, the first six rows would have been in pairs at Magny-Cours 1992:
Mr. Brundle was again to blame for upsetting the potential symmetry at Spa in 1988: he was standing in for an unwell Nigel Mansell. If only Nigel had been there...
And finally, another contender - Suzuka 1998 would have had the first seven rows in pairs, if that Mr. Schumacher wasn't quite so fast...
Ironically of course, Schumacher stalled in that race and dropped to the back.
