[CMT8.4.1.1209]When the data type aren't same for two columns of two table, the data type is used the column of target table

1 Create two tables in mysql
create table cmt(a int, b int);
create table cmt1(a char(3), c int);
2 Choose the two table to do migration from online to online.
change target tables for the two tables to cmt1,

The target table will be as follows:
Create table cmt1(a int, b int, c int);

Additional:
If change target tables to cmt, the target table is cmt(a int, b int, c int).
If change target tables to cmt2, the target table is cmt2(a int, b int, c int) too.

Suggest:
If change target table to one table which existed, it will choose the target table data type.

such as:
If change target tables to cmt1, the target table is cmt1(a char(10), b int, c int).
If change target tables to cmt, the target table is cmt(a int, b int, c int).
If change target tables to cmt2, the target table is cmt2(a int, b int, c int)