My present DNS configuration for my website's A record is as below

Name              Value
---------------------------
example.com       67.45.xx.xx
www.example.com   67.45.xx.xx

In above configuration user can open website either by example.com or by www.example.com.

One of my SEO team-member argues for single point access.
According to him search engine’s crawler see 2 different name with same content. It is not good and we should configure domain in such a way that if user open example.com then browser automatically get redirected to www.example.com.

Now I have 2 questions

1. Does above argument is valid?
2. If yes then what changes I need to do in my DNS?