There is no issue with flying two 7 hr flights separated by 1 night, in a modern well equipped IFR aircraft, and I have done plenty of ~7hr flights in the TB20, but it will be IMHO extremely tedious not least because the two flights are going to be over the same ground, and getting a reasonably good night's sleep will be more important than usual.
Personally I would choose to stop for 2 or more nights, at that kind of distance. Budapest is quite a pretty town
And you can have an hour in a 7M euro full motion 747NG sim for 300 euros, at the Malev place at the airport
In these situations, if the trip is important on the date(s), one normally buys a backup airline ticket.
Gasax - don't drag others down to your (apparent) level. That is an awfully English habit, and it never does anybody any good.