That's like having 6 people, but a car that seats 5.
You don't want to pay for a bus/taxi for the extra, nor do you want to get a new car to accommodate.
That person gets left behind (ie you don't use that fan).
Considering two of those fans are probably paired together as (front?) intakes, a splitter is exactly what you need here.
And they cost only a few $/Pounds/Euro.