Technically, you can have two Zyte Smart Proxy Manager(formerly Crawlera) addons in your subscription, e.g. C100 and C10, but only the higher one will have effect, so it's not recommended. What is recommended is to create another Scrapy Cloud organisation and subscribe to the other CXX plan there. This will ensure that both plans are active independently to suit your use-case (separating production and development accounts, for instance).