The interviewer wants to know how well you can multi-task. As we all know, you can't efficiently multitask without one of the tasks somewhat suffering. Don't fall for this trick question. If the situation comes up that you have two pieces of equipment that are both needing to be repaired, you could always troubleshoot one while the other was calibrating. You want to let the interviewer know that you give 100% attention to one piece of equipment at a time to avoid errors.
"When I repair equipment I give each piece 100% of my attention and time. I feel if I was distracted by the second piece of equipment I might make an error resulting in wasted time and money. I will troubleshoot one piece of equipment while the other is calibrating, and call a junior technician to assist me."
"If I were asked to fix two pieces of equipment, simultaneously, I would ask a few pertinent questions to determine which piece was the true front-runner for urgency. I would ask which piece of equipment affected productivity the most. Also, I would ask if there were a critical patient situation at hand. I would choose which piece to address first; once those answers were provided."
"If there were a situation where two pieces of equipment needed repair, I would assign the maintenance to two different technicians and oversee each job. I feel that equipment needs to have the full attention of the technician so asking them to multi-task isn't something I ask of my technicians."