System.Data.SQLite

This is somewhat related to the issue found at ticket #52816622f3, but there are a couple differences.

My sample project reads and inserts data from a table to a copy table.  When the first value inserted is an Int64, the following values are also inserted as Int64 even if they're being passed in as Doubles.

But if the first value inserted is a Double, then the rest are treated as Doubles and I don't lose any precision.

Please change your code to do this:

insertCommand.Parameters[0].ResetDbType();
insertCommand.Parameters[0].Value = reader.GetValue(0);

insertCommand.Parameters[1].ResetDbType();
insertCommand.Parameters[1].Value = reader.GetValue(1);