Bind address error in log

I added some ip address to system via command
ip addr add xx.xx.xxx.xxx/27 brd + dev eth0 label eth0:1
ip link set eth0:1 up

I use nginx as proxy server
proxy_bind xx.xx.xxx.xxx;
proxy_pass http://....

A couple of days ago in log I noticed errors, and server begin response error 500:
many of these errors
[crit] 23847#0: *89273 bind(xx.xx.xxx.xxx) failed (98: Address already in use) while connecting to upstream

How me fix it?