A total of 4168 centuries have been scored in Tests up to Oct 25, 2019 (not counting one scored in the World XI v Aus Test in 2005).
There have been 86 instances of centuries in both innings.
Details can be seen on this link: http://stats.espncricinfo.com/ci/engine/stats/index.html?class=1;filter=advanced;opposition=1;opposition=2;opposition=25;opposition=29;opposition=3;opposition=4;opposition=40;opposition=5;opposition=6;opposition=7;opposition=8;opposition=9;orderby=start;qualmin1=2;qualval1=hundreds;size=100;spanmax1=25+Oct+2019;spanval1=span;team=1;team=2;team=25;team=29;team=3;team=4;team=40;team=5;team=6;team=7;team=8;team=9;template=results;type=batting;view=match
38 of these resulted in victories, 11 in losses and 37 in draws.
3 players have achieved this on 3 occasions: SM Gavaskar, RT Ponting and DA Warner.
10 players have achieved this on 2 occasions: AR Border, GS Chappell, PA de Silva, R Dravid, ML Hayden, GA Headley, JH Kallis, KC Sangakkara, H Sutcliffe, BRM Taylor and CL Walcott. Walcott did this in the same season.
And 57 did this on one occasion.
EH Weekes scored his 2 centuries in a sequence of 5 centuries in successive innings.
6 did so as captain: Border, IM Chappell, Gooch, Inzamam, Melville and RB Simpson. Of these, Melville’s 2 hundreds came in a sequence of 4 centuries in successive innings (with World War 2 intervening).
Two players have scored a triple hundred and hundred in the same Test: Gooch (1990) and Sangakkara (2014).
The following players have scored a double hundred and hundred in the same Test (in chronological order):
KD Walters (1969)
SM Gavaskar (1971) in debut series
LG Rowe (1972) on debut
GS Chappell (1974); his brother IM Chappell scored a century in each innings of the same Test.
BC Lara (2001); The only such instance on the losing side. His total of 221 + 130 = 351 is the highest match total in a losing side.
To be continued.