If I have a popliteal aneurysm, will I have other aneurysms in the future?

Possibly. The popliteal artery is the third most common location for a aneurysm. These frequently occur in both legs. Patients who have one aneurysm are more likely to develop others in the aorta and femoral ( groin ) and iliac arteries. These patients are followed closely for early detection.
More likely than not. Popliteal artery aneurysms occur with a bilateral presentation in over 50% of patients. AAA is also diagnosed in around 50% of patients presenting with popliteal aneurysms. Ultrasound tests can evaluate this possibility easily. Your risk to develop additional aneurysm where there currently is none, is hard to define, but certainly elevated.