anycubic i3 mega with non-standard "Steps per unit" settings?

[w_m0zart]

Last weekend I acquired a used anycubic i3 mega 3d printer which somehow only prints correctly if I set the so-called "Steps per unit" to the double value. So with gcode, from following original setting

M92 X80.00 Y80.00 Z400.00 E92.60  <--- (Default settings)

I had to issue following gcode command/setting:

M92 X160.00 Y160.00 Z800.00 E185.20 <--- (My changed value)

Is this normal? I have not found anyone on the internet with this non-default setting.

Is there another way to get the same result, while keeping the original default setting?

Any help would be appreciated.

Some background:
With the latter setting the manual moving of the X-, Y-, and Z-directions in each 0.1, 1 or 10mm steps works as expected. With that also the printing of a 10x10x10mm block has the correct dimensions. Without that change, everything shrinks to half the distance, so manual moving in steps of 0.05mm, 0.5mm or 5mm. Also the 10x10x10mm block comes with some imagination (Since the filament smears and does not stick) out as a 5x5x5mm blob. I find this strange because this setting looks like the factory default setting. (When comparing output of other users on the internet.)

Does someone have an explanation why the settings for the steps per unit need to be doubled?

The stepper drivers are still the original DRV8825. The steppers themselves are still the original ones (BJ42D20-11V03) with 1.8?/step rotation. Also all spindles are unchanged.

Firmware is V1.1.2 ( V1.1.2_20181008 ), controller board is the trigorilla1.1