[!] means verified good dump - someone played it all the way through and found no glitches.
[bx] means it is a bad dump. Toss it.
[hx] means it is a hacked version. Someone bastardized the game by changing something in it. Toss it, unless it is interesting.
[tx] means it is a trainer. It has been hacked to make it easier to play.
The Letters in parenthesis indicate the language or region the ROM is from. choose (U) if you want USA. (E) is europe (J) is japan, etc.
The (M3) Means it has 3 different languages on it.
From your list I would keep the second one.
BTW - each file works independantly and you do NOT need to keep them all.
Edit: Here's some more detailed info:
STANDARD CODES:
[a] Alternate
[p] Pirate
[b] Bad Dump
[t] Trained
[f] Fixed
[T-] OldTranslation
[T+] NewerTranslation
[h] Hack
(-) Unknown Year
[o] Overdump
[!] Verified Good Dump
(M#) Multilanguage (# of Languages)
(###) Checksum
(??k) ROM Size
ZZZ_ Unclassified
(Unl) Unlicensed
Special Codes:
-----Gameboy
[ [C] Color ]
[ [S] Super ]
[ [BF] Bung Fix ]
---------Super Nintendo----
[ (BS) BS ROMs ]
[ (ST) Sufami Turbo ]
[ (NP) Nintendo Power ]
--------Atari---------
[ (PAL) Euro Version ]
-----Genesis-----
[ (1) Japan ]
[ (4) USA ]
[ (5) NTSC Only ]
[ (8) PAL Only ]
[ (B) non USA ]
[ [c] Checksum ]
[ [x] Bad Checksum]
[ [R-] Countries ]
---------GBA----------
[ [hI??] Intro hacks ]
--------Coleco--------
[ (Adam) ADAM Version ]
--------NES/FC--------
[ (PC10) PlayChoice 10 ]
[ (VS) Versus ]
[ [hFFE] FFE Copier fmt]
--NeoGeo Pocket--
[ [M] Mono Only ]
COUNTRY CODES
(1) Japan & Korea
(4) USA & BrazilNTSC
(A) Australia
(J) Japan
(B) non USA (Genesis)
(K) Korea
(C) China
(NL) Netherlands
(E) Europe
(PD) Public Domain
(F) France
(S) Spain
(F) World (Genesis)
(FC) French Canadian
(SW) Sweden
(FN) Finland
(U) USA
(G) Germany
(UK) England
(GR) Greece
(Unk) Unknown Country
(HK) Hong Kong
(I) Italy
(H) Holland
(Unl) Unlicensed
STANDARD CODE NOTES
[a] This is simply an alternate version of a
ROM. Many games have been re-released to
fix bugs or even to eliminate Game Genie
codes (Yes, Nintendo hates that device).
[b] A bad dump often occurs with an older
game or a faulty dumper (bad connection).
Another common source of [b] ROMs is a
corrupted upload to a release FTP.
[f] A fixed game has been altered in some way
so that it will run better on a copier
or emulator.
[h] Something in this ROM is not quite as it
should be. Often a hacked ROM simply has
a changed header or has been enabled to
run in different regions. Other times it
could be a release group intro, or just
some kind of cheating or funny hack.
[o] An overdumped ROM image has more data
than is actually in the cart. The extra
information means nothing and is removed
from the true image.
[t] A trainer is special code which executes
before the game is begun. It allows you
to access cheats from a menu.
[!] Verified good dump. Thank God for these!