Rummikub Joker Rules
It may or may not be legal, depending on which rules you're using. Some rulesets require you to match a joker retrieved from the board with two tiles from your hand for the new meld -- prohibiting you from using both jokers from the board together with only one tile from your hand.
See the discussion of &quot;Variations&quot; under https://www.pagat.com/rummy/rummikub.html

A lot of confusion has been caused by the rule from the &quot;Official Rummikub® Book&quot; that says that when a melded joker is replaced it must immediately be used in a &quot;new&quot; meld. What restriction, if any, does this place on the way the retrieved joker has to be used? The rules supplied with various editions of Rummikub® sets have interpreted this rule in different ways.

A still stricter interpretation, which seems to be preferred by many players, is that the joker must be reused in a new meld formed by combining it with two tiles from your hand. I have seen two sets of rules which support this view. The J W Spear &amp; Sons rules (1988) say: &quot;A joker that has been picked up in this manner must be used in that player's same turn, as part of a new set, along with tiles from his rack.&quot; The Pressman Toy Corp rules (1987, 1998) say even more explicitly: &quot;A joker that has been replaced must be used in the player's same turn with 2 or more tiles from his rack to make a new set.&quot; But even this is ambiguous: it is not clear whether the new set can also contain tiles from the table. Some players allow this. For example: on the table is a set of four 4's and a run of blue 8-7-joker; in your hand you have two blue sixes and a blue three; you may substitute one blue 6 for the joker and make a new blue run of 6-joker-4-3, stealing the blue 4 from the set of 4's. The new run uses two tiles from your hand, along with the joker and one other tile from the table.