Inform here your 'yum list nginx --showduplicates'.
Look like related to module in nginx. Possible different repo have different issue related to nginx.
Installed Packages
nginx.x86_64 1.7.1-1.el6.ngx @mratwork-nginx
Available Packages
nginx.x86_64 1.0.5-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.0.6-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.0.7-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.0.8-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.0.8-2.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.0.9-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.0.10-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.0.11-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.0.12-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.0.13-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.0.14-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.0.15-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.0.15-5.el6 epel
nginx.x86_64 1.0.15-5.el6 mratwork-epel
nginx.x86_64 1.2.0-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.2.1-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.2.2-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.2.3-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.2.4-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.2.5-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.2.6-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.2.6-6.el6.art atomic
nginx.x86_64 1.2.6-7.el6.art atomic
nginx.x86_64 1.2.7-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.2.7-8.el6.art atomic
nginx.x86_64 1.2.8-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.2.8-9.el6.art atomic
nginx.x86_64 1.3.15-1.el6.ngx mratwork-nginx
nginx.x86_64 1.3.16-1.el6.ngx mratwork-nginx
nginx.x86_64 1.4.0-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.4.1-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.4.1-11.el6.art atomic
nginx.x86_64 1.4.2-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.4.2-13.el6.art atomic
nginx.x86_64 1.4.3-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.4.3-14.el6.art atomic
nginx.x86_64 1.4.4-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.4.4-15.el6.art atomic
nginx.x86_64 1.4.4-16.el6.art atomic
nginx.x86_64 1.4.5-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.4.5-17.el6.art atomic
nginx.x86_64 1.4.6-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.4.6-18.el6.art atomic
nginx.x86_64 1.4.7-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.4.7-19.el6.art atomic
nginx.x86_64 1.4.7-20.el6.art atomic
nginx.x86_64 1.5.0-1.el6.ngx mratwork-nginx
nginx.x86_64 1.5.1-1.el6.ngx mratwork-nginx
nginx.x86_64 1.5.2-1.el6.ngx mratwork-nginx
nginx.x86_64 1.5.3-1.el6.ngx mratwork-nginx
nginx.x86_64 1.5.4-1.el6.ngx mratwork-nginx
nginx.x86_64 1.5.5-1.el6.ngx mratwork-nginx
nginx.x86_64 1.5.6-1.el6.ngx mratwork-nginx
nginx.x86_64 1.5.7-1.el6.ngx mratwork-nginx
nginx.x86_64 1.5.8-1.el6.ngx mratwork-nginx
nginx.x86_64 1.5.9-1.el6.ngx mratwork-nginx
nginx.x86_64 1.5.10-1.el6.ngx mratwork-nginx
nginx.x86_64 1.5.11-1.el6.ngx mratwork-nginx
nginx.x86_64 1.5.12-1.el6.ngx mratwork-nginx
nginx.x86_64 1.5.13-1.el6.ngx mratwork-nginx
nginx.x86_64 1.6.0-1.el6.ngx mratwork-nginx-stable
nginx.x86_64 1.6.0-21.el6.art atomic
nginx.x86_64 1.7.0-1.el6 mratwork-centalt
nginx.x86_64 1.7.0-1.el6.ngx mratwork-nginx
nginx.x86_64 1.7.1-1.el6.ngx mratwork-nginx