That previous employer thought that my backup and I shared the duties equally. They also thought that we had the same skills relating to supporting both the Windows servers and the HCL Domino application layer running on them. They found out while I went on my first lengthy vacay that he did not know SFA when it came to any problems above what was termed L1 - Help Desk/Service Desk level. Ergo, the calls the first few times I went away on vacation.
At the time I left that place near the end of July 2016, that IT Services company was supporting two (2) large HCL Domino clients and the Management thought my backup could easily handle the same workload. I sensed that they were gonna crash and burn with regards to those two clients. Before we reached the middle of August of 2016, I received a somewhat frenetic call from my previous Director saying "Starecase, we've got a problem."
Knowing where this phone call was likely headed, I really resisted the urge to say "Umm no ... it's YOU guys that have a problem."
After some near begging, borrowing and stealing from that Director, we agreed that they would set-up a 6 month contract for me and I would continue to support the tougher problems and application design issues for these two clients. And in that time, they were supposed to find another Starecase. They did 2 more 6 month deals that ran until the end of 2017 when they finally hired that more skilled person to slide into my old role.
And here's the kicker that I still chuckle about some 6 years later. I found out that in the summer of 2018, 6 months after the new guys was hired, BOTH of those contracts were lost to other providers.