#!/bin/bash
awk '{sub(/^[0-9]{4}[ \t]+[0-9a-z \t]+/, ""); s = (s == "" ? "" : s " ") $0} s && !NF {print s; s=""} END {print s}'
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0000 00 fe 51 53 c4 45 a4 72 4d cf 12 f4 06 02 46 00 ..a1...c].....d.
0010 06 33 c5 ft 43 30 64 04 b3 90 c6 f4 c8 e4 0a 00 .6..@.f... . ...
0020 23 54 cd 32 45 52 .3.2..
0000 00 fe 51 53 c4 45 a4 72 4d cf 12 f4 06 02 46 00 ..a1...c].....d.
0010 06 33 c5 ft 43 30 64 04 b3 90 c6 f4 c8 e4 0a 00 .6..@.f... . ...
0020 23 54 cd 32 45 52 .3.2..