Hot Platform-as-a-Service startup DotCloud is acquiring fellow PaaS startup Duostack in an attempt to gird itself for a fight that’s likely to leave some casualties in the years to come. With PaaS startups proliferating and large vendors such as VMware (s vmw), Red Hat (s rht), Microsoft (s msft) and Salesforce.com (s crm) already in the game, DotCloud and Duostack are making a smart move to ensur