I would like to know, does it make difference if the volume of eluent is more eg. added 500 microliter instead of 50 microliter? Does it differ in DNA concentration?
In case you can mix the DNA samples and their are no comparative studies that you are doing, you could go for lypholization of DNA which will concentrate the DNA present into powder form.
The eluted DNA concentration will be 10 times less if the elution volume is 10 times more as the amount of DNA adsorbed on the silica colun is limited... SpeedVac, EtOH precipitation or repeating the purification on minicolumn are alternatives to reduce the final volume.
In fact, your DNA concentration would be 10 times lower than if you add only 50 micros, if this concentration is suitable for your experiments, you don't need to repeat it furthermore, if not you can concentrate it by DNA lyophilization or repeating purification.