The new Kitty is to aggressive with the other [duplicate]

Question

We had a kitten (Gala) for a couple of weeks and she is the sweetest thing ever. Always playing and following us. So we decide to take another kitten now that the first one is still a little so they can be together when we are working. So finaly when this other kitten (Jasnah) Arrived Gala wanted to be friends and play but Jasnah is way to agrevise with her. Hissing and attacking Gala when she gets to close, playing with the toys with us but as soon as she realised is us running away. I'm not sure if this justd a matter of time or if here is a more serious problem and I'm worried about them. For the moment when have to separate them because gala is going to play and I'm worried that jasnah is going to Hurt her.