i just read about your comparison Miami and Explorer; good idea to justifiy, if they are clones or not!
But i am afraid, it is more difficult than expected...
Ok, i set up my Miami and its successor, the Advanced Travel Chess (same case, only silver colored) to the same settings.Steve B wrote: i pitted them against the CM9K Josh age 9 personality ( 1800 USCF) with pondering OFF
both computers had Pondering OFF,Books OFF , Random OFF and Selective Search ON
Time control was Game 30 Minutes..
the Mephistos had White..
First, both refused to play 1.d4 after hitting "Enter"; they always played 1.g3 (without book), so i interrupted the thinking process, when they had 1.d4 in mind[White "Mephisto Miami/Explorer"]
[Black "Josh - Age 9 #2"]
[Time Control "Game/30 Min.]
1.d4 Nf6 2.Nf3 d5 3.e3 c5 4.dxc5 e5 5.Nxe5 Bxc5 6.Nd2 Nc6 7.Bb5 O-O
8.Nxc6 bxc6 9.Bxc6 Rb8 10.Nb3 Qb6 11.Bxd5 Nxd5 12.Qxd5 Bd6 13.O-O Rd8 14.Qh5 Bb7 15.Nd4 Bf8 16.c4 Rbc8 17.b3 Qg6 18.Qxg6 hxg6 19.Rd1 Be7 20.Bb2 Bf6 21.Rd3 Rd7 22.Rad1 a5 23.h3 a4 24.Kf1 axb3 25.axb3 Ra8 26.b4 Ra2 27.R1d2 Rc7 28.Rc3 Ra4 29.b5 Rcxc4 30.Rxc4 Rxc4 31.Rd1 Rc5 32.b6 Rd5

i let them both show the following info: first move (+rd:1), Eval, depth, nodes. Especially the nodes shown were very interesting!
At most of the moves the nodes were slightly different between the Miami and the ATC (about +/- 20 nodes), but at some moves the nodes were absolutely identical (shown about 3-5 times per move)
Nevertheless they both played the same as your Miami resp. Explorer until move 20 were your Miami/Explorer and my ATC played 20. Bb2, but my Miami played 20.h3.
So i am afraid, even with random off, there is a slight factor of randomness left...
Or there is more than one Miami version?
BTW.: Richard Lang's Genius has a comparable behaviour. Even with "Random off" it sometimes plays different moves, when running test positions repeatedly...
best regards,
Robert
P.S.: sorry for this late reply to your post, but i don't read here so often at the moment...