LB activates all domains causing high CPU and RAM

Hi, after the accident of recent days I’m having big problems with the LB.
In practice I have 2 physical servers, where on the first server I have the domain and, on the second similar server I have and Before the accident everything was fine, now practically and and the two on both servers are used, consuming a lot of CPU and RAM, whereas before only was used on the two server. The problem is causing several inconveniences because in practice 4 sites are active instead of just 2. I have done various configurations on the IIS side but nothing has been done. Currently a.mydomain and mydomain are 2 separate instances on IIS but they point to the same folder, the same for the second server. I had to limit a.mydomain and b.mydomain at IIS level because otherwise they would block saying that I had reached maximum traffic, this problem never happened even when I only had one more server. At the moment we don’t have any significant users. What can I check to understand, otherwise I will have to abandon the solution that worked perfectly before this accident. Thanks in advance.