Thanks for your response.
I am still facing the same issue, Please see the output of apt-cache policy command.
lava-server: Installed: 2017.7-1~bpo9+1
Candidate: 2018.2-1+stretch
Version table:
2018.2-1+stretch 500
500
https://images.validation.linaro.org/production-repo stretch-backports/main i386 Packages
*** 2017.7-1~bpo9+1 100
100 /var/lib/dpkg/status
2016.12-2 500
500
http://ftp.us.debian.org/debian stretch/main i386 Packages
lava-dispatcher: Installed: 2017.7-1~bpo9+1
Candidate: 2017.7-1~bpo9+1
Version table:
*** 2017.7-1~bpo9+1 100
100 /var/lib/dpkg/status
2016.12-1 500
500
http://ftp.us.debian.org/debian stretch/main i386 Packages