There have been a total of five Test captains with the surname Smith: before Graeme and Steve, there were Aubrey Smith (who captained England in his only Test, against South Africa in 1889, before going on to a rather lengthier career as a Hollywood actor), Mike Smith (25 matches as captain of England in the 1960s) and Ian Smith (who was New Zealand's regular wicket-keeper in the 1980s and early 90s, and captained them once). It is indeed the most common surname among Test captains, the others to have produced more than one being:
FOUR:
Khan - Majid, Imran, Moin, Younis (all Pakistan)
Taylor - Herbie (South Africa), Mark (Australia), Ross (New Zealand), Brendan (Zimbabwe)
THREE:
Ahmed - Ghulam (India), Imtiaz (Pakistan), Saeed (Pakistan)
TWO:
Brown - Bill (Australia), Freddie (England)
Carr - Arthur, Donald (both England)
Chappell - Ian, Greg (both Australia)
Cowdrey - Colin, Chris (both England)
Crowe - Jeff, Martin (both New Zealand)
de Silva - Somachandra, Aravinda (both Sri Lanka)
Gilligan - Arthur, Harold (both England)
Goddard - John (West Indies), Trevor (South Africa)
Grant - Jackie, Rolph (both West Indies)
Gregory - Dave, Syd (both Australia)
Mann - Frank, George (both England)
Pataudi - Nawab senior and junior (both India)
Richards - Alfred (South Africa), Viv (West Indies)
Richardson - Vic (Australia), Richie (West Indies)
Note: the Chappells, Crowes, Gilligans and Grants were brothers; the Cowdreys, Manns and Pataudis were father and son; Majid and Imran Khan were cousins; Dave and Syd Gregory were uncle and nephew. All the other namesakes were unrelated.
Michael Jones/Arnold D'Souza
Michael Jones/Arnold D'Souza