Police said a youth armed with a knife targeted a 29-year-old man on Wakefield Road at around 10pm on Monday and demanded he hand over his mobile phone and wallet.
The victim was able to distract the suspect and fled. The suspect made off empty-handed.
The suspect was described as mixed race, 15 to 17 years of age, approximately 5ft 9ins tall and of very slim build.
He had unkempt facial hair and spoke with a Huddersfield accent.
The second incident happened same location at around 10.20pm.
The victim, an 18-year-old man, was approached by a youth of a similar description, also in possession of a knife.
The suspect threatened the victim, who then handed over his mobile phone and wallet, before making off in an unknown direction.
Both incidents happened near Wakefield Road's junction with Colne Street.
Detective Constable Ian Carruthers, of Kirklees CID, said: “Thankfully, neither victim in either incidents were injured, but have been left extremely shaken.
“We believe the suspect may have been the same in both incidents, but we are keeping an open mind.
“I would appeal for anyone who recognises the description of the man or who witnessed either incident to get in touch with police.
“I would also like to hear from anyone who saw anyone acting suspiciously in the Wakefield Road area on Monday night.”
Anyone with information is asked to contact Kirklees CID on 101 quoting crime reference 13170374713.
Information can also be passed anonymously to independent charity Crimestoppers on 0800 555 111.