The phrase "doubly lucky" is correct and usable in written English.
It can be used to describe a situation where someone feels fortunate in two different ways or has two sources of good fortune.
Example: "After winning the lottery and receiving a promotion at work, I feel doubly lucky this month."
Alternatives: "twice fortunate" or "twofold lucky."
Some have recently left Syria, and feel doubly lucky to be alive.
So I've been doubly lucky, darling!" Francesca died in January last year.
Historians were doubly lucky with the worshippers at Ben Ezra, who not only deposited written texts into the genizah, but, for some reason, never buried its contents.
I felt doubly lucky when the two new artistic directors of the award-winning Theatre 503 in Battersea, Tim Roseman and Paul Robinson, invited me to direct the plays as part of their opening season.
Of course, cooking would not be considered nearly so therapeutic if it did not offer the opportunity to confront various childhood traumas, so I count myself doubly lucky every month or so to have the opportunity to cook in my mother's kitchen.
To succeed at this, you must be doubly lucky: First, time the downturn correctly; and second, time the market's recovery precisely.
A lucky chancellor doubly blessed with a less lucky opposition.
These were all easily missed snippets, making them doubly special for those determined or lucky enough to be in attendance.
Sometimes you get lucky when traveling, and I felt doubly so: I'd found a guide and I'd made a friend.
He was lucky enough to get posted to Northern Ireland during the Troubles, and doubly blessed when the very same job took him to revolutionary Iran for a while.
Startup outcomes are unpredictable, and the outcomes of their investors doubly so, because it's hard to say whether the big successes are repeatable, or if the investors just got lucky.
