I am kinda not sure if this is correct, but I have read a grammar book in which the author said one of the repeated article can be omitted in a sentence, for example:
1) The dog has a long tail and a long body
He said the sentence above can be re-written like this:
1.b) The dog has a long tail and long body.
I doubt if he is correct.
Look at the following example,
Peter has a black and a white cat.
It means Peter has both a black cat and a white cat.
However, if the indefinite article in the second part is omitted, for example,
Peter has a black and white cat.
That means Peter has only one cat which is black and white in colour.
Did you see the differences, kwfine?
(Not a teacher)