[CMT8.4.1.1209]When change table name, then click other place, some target column will be lost

1There are two tables in mysql
Create table cmt(a int, b int);
insert into cmt values(1,1),(2,2),(3,3)
Create table cmt1(a int, c int);
insert into cmt1 values(1,1),(2,2),(3,3)

2 Migrate from online to online
3 Goto step3, choose the two tables. and change target table of cmt to cmt1. Then click other space.

Actual result:
The target column of b will be empty.

Analyse:
If the reason is the columns of cmt and cmt1 are different, I change target column of b to c, after migration, it will create table like as follows:

"CREATE TABLE "cmt1"(
"a" integer,
"c" integer,
"c" integer
)
;"

Please consider the requirement of it.