As chins are territorial you cannot simply put 2 together and hope they will get on as its very doubtful it will happen as you have found out. You need to introduce them slowly with 2 cages side by side for a number of weeks / months . You can swop them over into one anothers cage to allow them to get used to the others scent. Then give them a supervised playtime in a safe neutral area ( not where their cages are ) it may take a few weeks or even months before the accept one another
However if these chins have come in as rescues/rehomes and the male is not castrated I would not suggest allowing them to live together, you wont have any genetic history so you could well be breeding from chins that may be carrying genetic defects / malloclussion . To be honest I am surprised at a rescue centre that allows unneutered animals to live together
