c 250 eat a loat of tonner

[robizhub]

I have a c250 and a job to print (16000 A3 the same file!)
The problem is the folowing:
In the first 10.000 print the 250 consumes a loat o magenta tonner.
In the second part the 250 consumes a loat of yellow tonner.
I don't understend this because is the same file and it has to consume the same quantity of tonner.
Thanks for read and possible help.

[pepper38_cnd]

How are you determining Toner Consumption?

[robizhub]

toner consumtion

Because is the same file (page) an the beginig with 1 magenta tonner I print aprox 1800 pages (counter) and now with 1 magenta tonner I print 2300 pages and with yelow aprox 700 - 800 pages (on the counter)
thanks for answer