my male is trapping the female but he is facing the wrong way is this normal with bristlenose plecs ?

I'm not sure what you mean by the 'wrong' way but he would have to be back end in to fertilise the eggs which are laid at the back of the cave. When he is fanning the eggs he stays head end in.

his head is facing the outside of the cave why sh is in the cave so he is in the cave backwards

That sounds right, but there is a video HERE that shows just what happens.

thankyou mate they have now spawned

the male is sat on eggs but another female is on his cave trying to get in there will he let her in also if he does will she eat the other eggs ?

Congratulations on your BN's spawning

It's not unheard of for a male to guard more than one clutch of eggs and your second female will not eat the first clutch

Your male should let the other female in as when they are in the mood im affraid your male will have no choice...
My male always takes on 2 batches of eggs at once and raises them fine....as for another female eating eggs, that shouldnt happen really....

As for the male with his head first, this is normally a come on sign to females, as he is showing off his bristles to any passing females, bristles immatate young fry and this is what turns the female on and attracts her towards his cave, but as for the female being in there already then this would be a keeping in process from your male, if he feels he can keep her in better this way then he will....

Normally i no when my male is ready for a spawn as like i said he will be face first out of his cave attracting females.......

thanks for the info mate the eggs have hatched and she is still tying to get in he is facing outwards now so hopfully i will get a double spawn