New copies of pdf creates whenever i edit or open the pdf, adobe version 11.5.0

I am using ASUS fonepad 7 tablet (model K00Z), android 4.3 jelly bean, adobe reader app version 11.5.0

Whenever i open up a pdf or edit it and exit adobe reader, a new copy of same pdf is created in adobe's folder with the integer suffix to original name.e.g.

Abc.pdf as Abc-1.pdf, Abc-2.pdf and so on..corresponding to number of times i open up pdf.

I dont want such copies to be created whenever i open up pdf and exit adobe reader. One thing i have noticed is, while exiting pdf(adobe reader) by using back button it says "document saved", might be at this point copy is created.

Please suggest me ways to resolve this problem.

Thanks