Neither is correct ...
The correct for the present perfect continuous is:
"I/we/you/they had been going," or
"He/she/it has been going."
The correct for the the past perfect simple is:
"I/we/you/they had gone," or
"He/she/it has gone."
The phrase "had already left" is grammatically correct. The phrase "had already been gone" is not grammatically correct.
Present perfect tense - have/has gone. Present perfect continuous tense - have/has been going. Past perfect tense - had gone. Past perfect continuous tense - had been going. Future perfect tense - will have gone. Future perfect continuous tense - will have been going.
they cant find their way back
Once in 1964.
Was is preterit. Gone! Clean cut. Has been is past "participle", of participate? That is, the emotion of the past act carries into the present, drags into the present as it is remembered and talked about.
had gone and has been gone are in past . had gone is sometime before he or she had gone but has been gone is long time before . had gone is compared to gone and has been gone is the superlative of all....
Since You Been Gone was created in 1976.
Never Been Gone was created in 2009-10.
Be is to have been as Go is to have gone.
'since you been gone, I can breathe for the first time'
Tell Me How Long the Train's Been Gone was created in 1968.
been there focus on destination. gone there focus on the trip.
Since you've been gone = Kelly Clarkson = on the album Breakaway in 2004
The duration of Since You've Been Gone - film - is 1.6 hours.
He has been gone for a least 10 weeks
"Been to" is used when you have visited a place and returned, while "gone" is used when you have traveled to a place but have not returned yet. For example, "I have been to Paris" means you visited Paris and returned, whereas "I have gone to Paris" means you have traveled to Paris but are still there.
been there done that