How to convert in OpenERP from one chart of account to another?
I don't know of any way to install another chart of accounts after you've run the initial configuration wizard on a new database. However, if all you want to do is change the account numbers, names, and parents to match a different chart of accounts, then you should be able to do that with a bunch of database updates. Either manually edit each account if there aren't too many accounts, or write a SQL or Python script to update all the accounts. To do that, you'll need to map each old account to a new account code, name, and parent, then use that map to generate a script.
I have installed chart of accounts A for company1. This chart was used couple months for accounting. How can I convert into chart of accounts B and keep old data for accounts (debit, credit, etc.)? In other words, is possible migrate data from one chart of accounts to another? Solution could be programmatically or trough web client interface (not important). Virtual charts of accounts can't be used. Chart of accounts B must became main chart with old data. 
Every advice will help me a lot. Thanks