Yes. Montblanc began around 1990 to mark its writing instruments with a serial number in the upper cap ring. The 144, the small Meisterstück, went on being built well beyond that point and was not discontinued until around 2000. A serial number on this model is therefore no argument against the identification; it merely dates the pen to the period after 1990. Older 144s without a number are just as original.
Conversely, a serial number is no proof of authenticity, since numbers, certificates and papers are forged as well. Authenticity can in any case be judged only to a limited extent from photographs; more reliable is an examination of the pen itself, in which the nib, the feed, the engravings, the cap ring, the standard of finish and the weight are considered in direct comparison with a known original, or at an authorised specialist dealer's.