import re
 
s = '''M1  hello world 1234_5678  ip som lorem  9321_1231  iste natus error sit voluptatem   4313_4351  ratione voluptatem sequi nesciunt   4312_1234
M2 magnam aliquam 4351_3143  sed quia non numquam  3123_1432'''
 
for x in re.finditer(r'^(M[12])?((?:\s+\D+\d{4}_\d{4})+)', s, flags=re.M):
	f = re.findall(r'\s+(\D+)(\d{4})_(\d{4})', x.group(2))
	print("\n".join(["{}\t{}\t{}\t{}".format(x.group(1), c[0], c[1], c[2]) for c in f]))
 
 

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