No, 2 t34 can be a threat to a tiger, but, 2 p4 hardly can threaten an is2. Both t34 and p4 have the same penetration values but the is2 has more armor values (especially front).
The key difference between the 2 armies in this comparison is the AT guns. The pak reloads so fast compared to the zis, but only has 10 more penetration at any range. That is why it struggles against the is2 high front armor.
Time to kill:
PaK40 vs IS2: (1040/160) / (190/375) = 12.82 * 3.9625 s/r = 50.8 secs
ZiS3 vs Tiger: (1040/160) / (180/300) = 10.8 * 5.8 s/r = 62.64 secs
far:
PIV vs IS2 (1040/160) / (100/375) = 24.4 *5.75 s/r = 140.3 secs
T34 vs Tiger (1040/160) / (80/300) = 24.375 *6.75 s/r = 164.5 secs
near:
PIV vs IS2 (1040/160) / (120/375) = 20.3 *5.75 s/r = 116.7 secs
T34 vs Tiger (1040/160) / (120/300) = 16.25 *6.75 s/r = 109.7 secs
Rear armor near:
PIV vs IS2 (1040/160) / (120/205) *5.75 = 63.8 secs
T34 vs Tiger (1040/160) / (120/180) *6.75 = 65.1 secs
In actual gameplay the T34s will do worse than this because they have worse survivability than the PIV (even if the only thing in the area is the Tiger/IS2, because the Tiger has higher DPS against mediums). Plus no smoke or blitz.