I received a 60 day visa back in March and would like to know if it can be extended in Vientiane for another month, and if so, will it be for free as was the origional double entry visa?

A tourist visa entry can be extended at any immigration office in Thailand for 30 days. The fee is 1900 baht.

You cannot extend a visa at an embassy, you can extend it at immigration in Thailand for 30 days at a cost of 1,900 baht.You can also go back to vientianne and ask for a new double entry tourist visa. They are free till june 4th.

But don't you already have a double entry visa? If so just cross the border and come back for another 60 days.

As said , extend at Immigration or apply for a double entry at Vientienne.