The South African scored 58 from 37 balls and 78 from 38 balls in Sussex's wins against Essex in Southend on Monday and Surrey at New Malden on Tuesday.
Inserted by the home side in the first match, Wiese helped Sussex to 160 for 9 from their 20 overs. Ravi Bopara (21 from 18) and Wiese added 53 for the fourth wicket, while there were cameos all the way down the order.
Bopara was the pick of Sussex's bowlers, taking 4 for 14 from 3 overs, as Essex were restricted to 142 for 7 in reply. There was a wicket each for Joe Sarro, skipper Will Beer and Wiese as Sussex completed an 18-run victory.
A full scorecard and video clips from the match are available here.
On Tuesday, a Sussex team led by Luke Wright and bolstered by a number of other Vitality Blast regulars - including the return from injury of Phil Salt - amassed 191 for 9 after winning the toss and batting. But it was Harrison Ward (49 from 37) and Oli Carter (27 from 18) who played the main supporting roles to Wiese, although Tymal Mills will have enjoyed his quickfire 14 from eight deliveries from number nine, including an enormous six off the bowling of Matt Dunn.
Mills (3-37) picked up three wickets in Surrey's innings, with Wiese (2-22) and Jordan Shaw (2-10) taking two each with an economy of less than a run a ball. Delray Rawlins (1-36) and Will Beer (1 for 26) were the other wicket-takers as Surrey were restricted to 163 for 9.
A full scorecard and video clips from the match are available here.
Sussex's play their next two matches in the competition against Middlesex on Thursday and Essex on Friday behind closed doors at The 1st Central County Ground.