Joined table shows data twice

[uschmi]

Table 1 has to left-joined tables. Both table 2 and table 3 are joined in the same way.
In form view of table 1, data of table 2 are showing correct but data of table 3 are showing twice (while the first part shows correct data and the second part shows empty data). See attached screenshot...

What I´m doing wrong???

 

[uschmi]

I found the reason/solution myself: table 1 and table 2 are of type myIsam, while table 3 was of type InnoDB. When changing table 3 to table type myIsam data are displayed correctly.