dapper, from the mature dates on both, I wouldn't think there would be a problem. The sunglo is around 64 days and about a month later for silver queen. Wouldn't think they would tassle at the same time.
Just my opinion.
Shot

dapper

I agree with Shot. You can plant corn varieties together as long as they have at least two weeks' difference in maturity dates.

You can probably plant the Early Sunglows at one foot apart, maybe even closer if you keep them well-watered and fertilized -- they grow only 4-6 feet tall. The Silver Queens are 8-10 feet tall and require more root-space.

Below is a relevant GardenWeb discussion

Here is a link that might be useful: Corn Spacing

SQueen is taller than the ESGlow so plant the ESunG on the south end of the bed so it won't be shaded out by the SQueen.

What are you worried about? Both are plain "SU" types so the only thing that could happen if they would happen to cross is a few yellow kernels on some white Silver Queen ears. And I agree with other comments but if you are concerned you can also just remove the Early Sunglow tassels as soon as the first Early Sunglow silks start to darken. But their maturity dates are closer to 3 weeks apart so you really won't even have to anything. Just enjoy.

dapper: Check out my post today under Corn density.