2 blades are 180 degrees apart. 3 blades are at 120°.
If your turbine is 1000 Watts, Fine, 2 blades are cheap. For industrial purposes select a 3-blade design. When one of two blades is in the low velocity low altitude sector, then passes through the stagnation region in front of the column while the high blade is in upper level higher velocity region, forces are unbalanced between blades, resulting in maximum moments applied to the shift and the variable load of the stagnation point induces vibration. A 3 blade configuration is a far more balanced design.

A black swan to a turkey is a white swan to the butcher ... and to Boeing.

Hi, thanks for reply..

But what I meant was not loads in operation. Excessive loads and moments in single blade installation (while building the turbine) is considered to cause local high stresses (maybe cracks) on drivetrain, which it is not intended to be designed for. This leads main bearing or gearbox to fail earlier than expected. Is it possible to prevent this phenomenon?

It's a load on a bearing. There are plenty of arrangements of bearings to manage loads like this. The main bearing needs to be designed for this; even with multiple blades the air flow is never uniform so there is always some oscillating loading.

They are typically mass-balanced so only the shifting aerodynamic load will need to be dealt with. Not a big deal - look at the drive pulley shaft on any engine - it sees an oscillating load and does fine.