[server] Error: Hostname A provided via SNI and hostname B provided via HTTP are different

Dear all,

I have an Ubuntu Server 14.04 LTS with Apache 2 configured as http/https proxy.
I have a valid wildcard certificate for the domain and multiple name based Virtualhosts with SSL, configured as in the following example:

<VirtualHost 192.168.0.1:443>
ServerName name.domain.it
ServerAlias name.domain.it
ProxyPass / http://intealhost.domain.it/
ProxyPassReverse / http://intealhost.domain.it/
ErrorLog ${APACHE_LOG_DIR}/error.log
CustomLog ${APACHE_LOG_DIR}/custom_log combined
SSLEngine on
SSLProtocol all -SSLv2 -SSLv3
SSLCipherSuite ALL:!DH:!EXPORT:!RC4:+HIGH:+MEDIUM:!LOW:!aNULL:!eN ULL
SSLCertificateFile /path/to/my/certificate.crt
SSLCertificateKeyFile /path/to/my/private_key.key
SSLCertificateChainFile /path/to/my/sub.class2.server.ca.pem
</VirtualHost>

For http all works very fine, but with https I have the following error:

a.domain.it and b.domain.it are both CNAME record
When I open the site https://a.domain.it/, the coection is established to the server.
After when I try to open https://b.domain.it/, sometime (4/5 times every 10 attempts ) apache retus a 400 Bad Request, and an error appears in the error.log file:

AH02032: Hostname a.doamin.it provided via SNI and hostname b.domain.it provided via HTTP are different

If I try to open again the site https://a.domain.it/ apache retus a 400 Bad Request,also for thi site and the following error appears in the error.log file:

AH02032: Hostname b.doamin.it provided via SNI and hostname a.domain.it provided via HTTP are different

On all https sites I have this problem randomly.

Have you any suggestions?