Diplopia usually occur due to anisometropia but in your case it seems to be due to poor quality of glass  ,go for either crizal,satin+ or G K V brand.It may be due to dryness also which is very common these days for which you can use some lubricating eye drops (Refresh liquigel) 4-5 times on trial basis for a week & see whether you get any difference.

Get a good quality glasses. Glass lenses with antiglare might help.

You have a condition called anisometropia where there is a big difference between the spectacle power of the two eyes. That is why your doctor has under corrected your power.( Giving u full correction would have caused double vision and strain). Since you are having symptoms with your current glasses, it seems your eyes are still not accepting the difference in power. 1)This problem may subside with time sometimes, but i think its better u get ur refraction done from a different place and see the difference 2)It could be because of poor qulaity glasses, so u can try higher quality glasses. 3) If this doesnt work, u could try contact lenses after consulting an ophthalmologist. But u will nedd toric contact lenses in the left eye, which are expensive. This will definitely eliminate ur diplopia.