"I am sending ten blue shirts."
Translation:Saya mengirim sepuluh kemeja biru.
There is already an indication of plurality ('sepuluh').
In such a situation, you don't reduplicate the noun.
'Saya punya satu kemeja' = I have one shirt.
'Saya punya sepuluh kemeja' = I have ten shirts.
'Saya punya banyak kemeja' = I have many shirts.