The best answer in IT for the question is 0 with a carry flag. Team building approaches have different answers they think it is more than 2 what is the math answer. Is there any cases when the result is less?

Assuming that the result is the value for money or the ability to change ratio in the architecture then yes, there are many cases when the performance will be much worse if you have 1+1 instead of tan appropriate 1.

The following stories are not real they did not happen neither mine nor your past!

Incompetent people

I so the case so many times, when different reasons drive to the situation when incompetent "trusted" people get a task to deliver. It happens for example why you start using "cheap" outsourcing services or vendors, having low rate card for their staff. The painful result is that you waste time, since the delivery will be delayed - assuming it will happen at all. Next pain point is, that whatever you will get is far from the expectations therefore you will ask another person internally or externally to revise, supervise the deliveries or to fix the bad results. This second guy is usually an expensive one. Take a special case, when the improper vendor offer to build the version of 2.0 of an existing application resulted 50% longer delivery than the original vendor offered, high extra cost towards the "cheaper" vendor and finally the original offered price from the "expensive" vendor to save the project, fix the problems and execute migration to the new application. A typical case when the wrong decision resulted to use 'one' vendor plus another 'one', while the whole cost was much larger then 'two'; and having the right decision, you would need only a single one!

The issue certainly exists on the other end too, when you take an over-experienced person to do the job and you feel after a while that you pay 1+1 instead of 1. The even worse case is when this high-price expert starts boring, generating more work as needed or simply leave you alone in the middle of nowhere...

Functional duplications

Did you ever hear the word of satellite applications? If you do I believe similar to me you remember for the negative meaning of this notion. The negativism is coming from those projects, programs when one start to believe in large "celeb" applications on the field of CRM or ERP for example and after a long while, which usually longer the planned project length you realise that the reality and the dreams are not playing in the same league. This is the time in the solar system when the satellites born to implement the "workaround" of the missing functions. This case you will have 'one' large application, 'one' set of satellites, the costs are much higher then it could be, while the ability to change is dramatically lower as it should.

If you have any other examples, please share it in the forum!