My text book provided me with 2 reactions concerning alkynes (Specifically Terminal Alkynes).
The first one was the dimerisation of an alkyne on passing it through ammoniacal $\ce{Cu2Cl2}$.
All was fine until I encountered the next reaction.
It was a test to distinguish between terminal alkynes and other alkene and alkynes.
It involved the fact that treating a terminal alkyne with ammoniacal $\ce{Cu2Cl2}$ would result in the alkyne forming a red precipitate as copper replaces hydrogen of one of the terminal hydrogen.
However now I was confused. Which of these reactions actually happens? Or are there specific conditions for each of these reactions that my text missed out?
Please help me in this aspect.