There are two roller coasters named Grizzly, both in Paramount parks - one at Great America and the other at King's Dominion. Both are wooden double out and back coasters, but they are not quite twins.

The Grizzly at Great America opened in 1986, ten years after the park's opening. The only woodie in the park, it was designed and manufactured by Curtis D. Summers and built by the King's Island Construction, Maintenance, and Engineering Department. It is 3,250 feet in length and 90 feet high; the main drop is 88 feet and the coaster reaches a maximum speed of 50mph. There are, of course, no inversions on the ride, and the duration is two minutes and forty seconds. Two trains can accommodate 28 riders each, and were designed by D.H. Morgan Manufacturing.

The King's Dominion version of the Grizzly opened in 1982 and was designed by the Taft Attractions Group, who modeled it after the Wildcat at Coney Island. Built by the King's Entertainment Company, the coaster is 3,150 feet in length and 87 feet high. The first drop is 85 feet, and the top speed is 50mph. Once again there are no inversions, and the ride takes two minutes and thirty seconds. The two trains, designed by the Philadelphia Toboggan Co., accommodate 28 riders each.

Sources
Great America Grizzly
http://www.rcdb.com/installationdetail77.htm
http://www.ultimaterollercoaster.com/coasters/yellowpages/coasters/grizzly_pga.shtml
http://www.coasterbuzz.com/coasters/coaster.asp?CoasterID=129

King's Dominion Grizzly
http://www.rcdb.com/installationdetail90.htm
http://www.ultimaterollercoaster.com/coasters/yellowpages/coasters/grizzly_pkd.shtml
http://www.coasterbuzz.com/coasters/coaster.asp?CoasterID=137