When onboarding Juniper EX4400-48T, Apstra automatically assigns Device Profile 'Juniper_EX4400-48T_EM-4Y' to it, instead of 'Juniper_EX4400-48T'.

With the current Apstra design, there is no way to control choosing either 'Juniper_EX4400-48T_EM-4Y' or 'Juniper_EX4400-48T', as they are the same hardware model but with different extended modules.

So you may have one DP or both mixed for your EX4400-48T devices when they are onboarded. You need to manually set the proper Device Profile in Managed Devices.