"Ποιο ξυράφι είναι δικό μου;"

[emaryod]

Could also be translated as Which is my razor?

[jaye16]

Yes, thank you I've added it.

[MarotSamay]

Why do we have to use both "δικό" and "μου"? Both words indicate possession/ownership.

[jaye16]

"Μου" can indeed stand alone and means "my". However, "δικό μου" must be used together as an expression and means "mine" "my own" it is more emphatic and it must agree with the noun in gender, case, and number.

See this comment for other info: https://forum.duolingo.com/comment/24409765