TLDR: It depends on your routing configuration.
You should check how routing is configured on your laptop.
1) In case you forward all traffic to the hot spot, the ISP (of the hot spot SIM) will see the IMEI of the hot spot SIM. The ISP of laptop SIM will not see anything, because you don't use laptop SIM.
2) You can also configure routing on your laptop so that traffic to some hosts is routed via your laptop SIM and traffic to some hosts routed via hot spot. Then the ISP of laptop SIM will see your IMEI when you access host A and the ISP of the hot spot SIM will see the IMEI of hot spot SIM when you access host B.
What should you do if you are worried? Check routing configuration on your laptop. If both network interfaces are active, you will see that your have 2 different IPs, 2 different network gateways, different DNS servers for each interface etc. Then adjust routing as you need.