Crosby followed Saturday's Premiership mauling of Peel with another convincing victory over their rivals in Sunday's Tinker Cup match.
They reached 203 for 5 in their allotted overs with Simon Watson hitting his second consecutive century, finishing on an unbeaten 108.
He was ably supported by Kevin Kniveton and Jack Rowlands, who both scored 27.
Russell Miller was the pick of Peel's bowlers, finishing with figures of 2-21 and also led their batting, scoring 29 as they could only muster 90 runs in reply.
Jacob Hicklin and Dave Picken laid into the Westerners' attack, picking up 4-25 and 3-14 respectively.
St John's avenged their Premiership defeat to Castletown by securing a comfortable 117 run victory at home.
Jon Norrington and Grant Atchison were the top batsmen with 44 and 37 respectively as the Saints were all out for 178.
Gareth Morris had a successful spell for Castletown, taking 4-11 while Greg Tomlinson picked up 2-19.
But Town could only manage 61 runs in their innings, Christian Steriopulos top-scoring on 15.
Daniel and Chris Hawke were in imperious bowling form; Daniel grabbed 4-0 and Chris got 3-6.
The other Tinker Cup match was a tighter affair as Ramsey beat Cronkbourne by 30 runs.
The Northerners were all out for 166; Ken Harding and Ollie Webster top-scoring with 38 and 24 runs respectively.
Neil Holmes finished with 3-15 for Cronkbourne while Alex Stokoe picked up 3-27.
Alex was the cream of the Cronkbourne crop at the crease but his 22 and Steve Clague's 20 weren't enough as the home side were bowled out for 136.
Ramsey's bowling attack was led by Chris McConnell (3-16) and Ken Harding (2-22).