all you show is the crystals and the switch, if they are 'a mile' away from the uC then the switch is not your problem.

few days ago my colleague insisted that this board has desytroyed his timing and when he cut tracks and shorted them like a simple single crystal connection ,it worked correctlly

If you are lucky and happen to have a very forgiving uC then you may get by with a switch, but the problem with the switch etc is that the burden capacitance (the combination of the capacitor and the stray capacitance) can be anything and will be different based on the position of the switch. Some uC.crystal combinations are very critical, some are just critical re burden capacitance. If you absolutely have to have a switch, then do everythig you can to lay out the PCB so the stray capacitance is the same regardless of the switch position. Now, of course, if you end up with two crystals that require different burden capacitances you are screwed regardless.

while you may get what you want to 'work' the permanent, reliable, guaranteed solution will be an external oscillator and possibly a PLL.

Erik