I've found a serious misbehavior when importing data. Gretl is getting rid of all underscores from series names. I'm attaching a simple .xlsx file that you can use to reproduce the error. The series are "teste", "teste_teste", "teste_", and "tes_te". After the command "open teste.xlsx" Gretl shows me the following names: "teste", "testeteste", "teste1", and "teste2".
I'm using the current snapshot on a Windows Vista PC.