Would just like clarification, Was told recently at c/m immigration that a re-entry was good for more than one trip in its 6 month validity ,true or not ??

single re-entry permit is for one re-entry (about 1000B)...

Or you might get multiple re-entry, that you can use again and again for the life of your visa, about 4000B...

As said a single re-entry at 1,000 baht is good for one re-entry prior to expiration date (same date as extension of stay stamp).

A multi re-entry at 3,800 baht is good for unlimited number of re-entry prior to expiration date (same date as extension of stay stamp).

A re-entry stamp has the same validity as the extension of stay stamp - so only if you have six months remaining on that stamp would the re-entry permit be valid for six months.

So the answer can be true or not true depending on what you have.