Dumvirs or Duumvirs: How To spell?
The word Dumvirs is misspelled against Duumvirs, which is plural of "Duumvir"
Duumvirs has double "uu" is mispronounced as "u"Remember double 'UU' in between the strings d & mvirs which should not be misspelled with single 'U'
Wrong Spelling:  d-u-mvirs  Correct Spelling:  d-uu-mvirs 
Check more misspelled words of Duumvirs to spell it correct.