This multi-talented performer was the Glamorgan batter Alan Rees, who won three rugby union caps for Wales in 1962, before turning professional and playing rugby league for Leeds. Rees was a superb fielder, and during the 1964 Ashes series caught Australia's Peter Burge for 160 while fielding as 12th man in the third Test at Headingley. "Burge swatted another short ball from Trueman straight into the hands of Glamorgan's Alan Rees, who was on the field at deep midwicket as a substitute," wrote Andrew Hignell. The following season, Rees was out "handled the ball" during Glamorgan's Championship match against Middlesex at Lord's. The Times explained: "Rees, sweeping at a ball on the leg side [from Fred Titmus], slipped. His bat swung away in his left hand and, as he fell backwards, he instinctively stopped the ball with his right, preventing it either from going on to the wicket or giving Murray a stumping chance."
That performance by Gautam Gambhir isn't quite the record, although it is the best for India, beating runs of four by Sunil Gavaskar, Rahul Dravid and Sachin Tendulkar. There are two other instances of five, by Jacques Kallis for South Africa in 2003-04, and Pakistan's Mohammad Yousuf during 2006.
The man most often out stumped in Tests is Allan Border, who fell that way nine times - although that did include three centuries, and overall he averaged 68 in those innings. Another Australian captain, Michael Clarke, was stumped eight times, as was the aggressive West Indian Clyde Walcott. A modern-day West Indian, Jermaine Blackwood, is among a group of six players out stumped seven times, including two more Australian captains in Ricky Ponting and Mark Taylor.
Lincoln Roberts, a batter from Trinidad's sister island of Tobago, played his one unproductive Test for West Indies against Australia in Kingston in 1998-99. Batting at No. 3, he was out seventh ball for a duck, and had to watch No. 4 Brian Lara make 213. West Indies won the match by ten wickets, so Roberts didn't get another chance, and was dropped for the next Test. He'd only scored one first-class century for T&T at the time, but added four more - including 220 against West Indies B in Couva in 2002-03. Still, he never got another call from the selectors.
There have now been 151 scores of 25 or more by the No. 11 in Tests, the highest being Ashton Agar's 98 on debut for Australia against England at Trent Bridge in 2013. But you're right that only one man did it in both innings: Ireland's Tim Murtagh, with 54 not out and 27 against Afghanistan in Dehradun in March 2019. Murtagh's half-century in the first innings was one of 19 in Tests by No. 11s, and he also provided only the 11th instance of the last man top-scoring in a Test innings.
Steven Lynch is the editor of the updated edition of Wisden on the Ashes