Reference

Space Shuttles on Both Launch Pads
 
STS 61-C (Columbia) and
STS 51-L (Challenger)
Dec. 22, 1985 (rollout of 51-L to Pad B) to Jan. 12, 1986 (launch of 61-C from Pad A)
 
STS-31 (Discovery) and
STS-35 (Columbia)
April 22, 1990 (rollout of STS-35 to Pad A) to April 24, 1990 (launch of STS-31 from Pad B)
 
STS-41 (Discovery) and
STS-35 (Columbia)
Sept. 4, 1990 (rollout of 41 to Pad B while 35 awaited launch on Pad A) to Oct. 6, 1990 (launch of 41)
 
STS-38 (Atlantis) and
STS-35 (Columbia)
Oct. 14, 1990 (rollout of STS-35 to Pad B) to Nov. 15, 1990 (launch of STS-38 from Pad A)
 
STS-37 (Atlantis) and
STS-39 (Discovery)
April 1, 1991 (rollout of STS-39 to Pad A) to April 5, 1991 (launch of STS-37 from Pad B)
 
STS-45 (Atlantis) and
STS-49 (Endeavour)
March 13, 1992 (rollout of STS-49 to Pad B) to March 24, 1992 (launch of STS-45 from Pad A)
 
STS-50 (Columbia) and
STS-46 (Atlantis)
June 11, 1992 (rollout of STS-46 to Pad B) to June 25, 1992 (launch of STS-50 from Pad A)
 
STS-56 (Discovery) and
STS-55 (Columbia)
Feb. 7, 1993 (rollout of STS-55 to Pad A) to April 8, 1993 (launch of STS-56 from Pad B)
 
STS-64 (Discovery) and
STS-68 (Endeavour)
Aug. 19, 1994 (rollout of STS-64 to Pad B) to Aug. 24, 1994 (rollback to VAB of STS-68 from Pad A)
 
STS-71 (Atlantis) and
STS-70 (Discovery)
May 11, 1995 (rollout of STS-70 to Pad B) to June 8, 1995 (rollback to VAB of STS-70 from Pad B)
 
STS-71 (Atlantis) and
STS-70 (Discovery)
June 15, 1995 (rollout of STS-70 to Pad B) to June 27, 1995 (launch of STS-71 from Pad A)
 
STS-70 (Discovery) and
STS-69 (Endeavour)
July 6, 1995 (rollout of STS-69 to Pad A) to July 13, 1995 (launch of STS-70 from Pad B)
 
STS-69 (Endeavour) and
STS-73 (Columbia)
Aug. 28, 1995 (rollout of STS-73 to Pad B) to Sept. 7, 1995 (launch of STS-69 from Pad A)
 
STS-73 (Columbia) and
STS-74 (Atlantis)
Oct. 12, 1995 (rollout of STS-74 to Pad A) to Oct. 20, 1995 (launch of STS-73 from Pad B)
 
STS-95 (Discovery) and
STS-88 (Endeavour)
Oct. 21, 1998 (rollout of STS-88 to Pad A) to Oct. 29, 1998 (launch of STS-95 from Pad B)
 
STS-103 (Discovery) and
STS-99 (Endeavour)
Dec. 13, 1999 (rollout of STS-99 to Pad A) to Dec. 19, 1999 (launch of STS-103 from Pad B)
 
STS-104 (Atlantis) and
STS-105 (Discovery)
July 2, 2001 (rollout of STS-105 to Pad A) to July 12, 2001 (launch of STS-104 from Pad B)
 
STS-125 (Atlantis) and
STS-126 (Endeavour)
Sept. 19, 2008 (rollout of STS-126 to Pad B) to Oct. 20, 2008 (rollback of STS-125 from Pad A)
 
STS-125 (Atlantis) and
STS-127 (Endeavour)
April 17, 2009 (rollout of STS-127 to Pad B) to May 11, 2009 (launch of STS-125 from Pad A)