Click on the little 'restore' box next to the "X" at the upper right corner of your Explorer screen. Then size the window to cover half your display by dragging the edges with your mouse; I make a window covering the left half of my screen but you can do top/bottom if you prefer. The click on "file", "new", and "window". You'll get another window open that's a duplicate of the original. Then put your cursor in the colored stripe at the top of the new window and drag it to the empty space you left on your desktop. You now have two independent windows active that you can use for sniping.

Note that you can open any number of windows at the same time, limited only by how small you can make them and still see something useful. I've opened as many as six at a time to snipe a seller that used the eBay facility to start all his auctions at the same time (and close at the same time, of course). You can preset the bids in the active bidding windows, watch the time in the monitoring window, and click the submit in each bidding window in rapid succession as the clock counts down to the close of all the auctions.

The ability to have several programs running at the same time at different spots on your computer screen was one of the major new ideas introduced by the Windows operating system back in the 90's.