Cisco 2960X stacked switches pop up ACL error messages without any ACL configured nor input

Question

I have a few Cisco 2960X with the fiber flexstack modules, when I boot them up, I always got these message:

'Duplicate sequence number.
Failed to add ace to access-list'

These are brand new switches without any config, all I did is install the stack modules and upgrade the switch IOS. And I have them on my desk when booting up with only console cable and stack fiber cables connected.
It doesn't seem to have affect the switches' functions, but I'm curious how could the switches spit out these prompt by itself.

Stack module: 2960X-FIBER-STK.
IOS 152-6-E2

Has anyone seen these behavior before?

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[Newest edit] Workaround/possible cause

This only happen with 152.6.E2, I just loaded 152.6.E and these annoying messages stopped.

[End of Newest edit]

Answers to some comment:

Thanks for the input.

Config - No there isn't configuration, I have also done 'write erase' to make sure, I have 6 sealed switches in total.

IOS - These fiber stack modules only work with 152.6.E2 or later, per Cisco stack module white book. I actually tried the gold starred version, 152.4.E7, it returns the 'smartchip authentication failed' and the stack ports will stay down down. And yes, I have loaded 152.6.E2 to all six switches, thus they have identical release, confirmed with show switch command.

Log - as I said there isn't config, the log doesn't show anything (except system up down, stack port up down)...Here is the output of a booting which I think is more relevant:

Election Complete<br>
Switch 2 booting as Member, Switch 1 elected Master<br>
HCOMP: Compatibility check PASSED <br>
Waiting for feature sync....<br>
Waiting for Port download...Complete<br>
Stack Master is ready<br>

Initializing Port Extension Feature Support...<br>


This product contains cryptographic features and is subject to United
States and local country laws governing import, export, transfer and...<br>
...emit...<br>
Last reset from power-on<br>
1 FastEthernet interface<br>
100 Gigabit Ethernet interfaces<br>
8 Ten Gigabit Ethernet interfaces<br>
The password-recovery mechanism is enabled.<br>

512K bytes of flash-simulated non-volatile configuration memory.<br>
..emit info...
Hardware Board Revision Number  : 0x19<br>

interface TenGigabitEthernet2/1/1<br>
           ^
% Invalid input detected at '^' marker.<br>

interface TenGigabitEthernet2/1/2<br>
           ^
% Invalid input detected at '^' marker.<br>

Press RETURN to get started!<br>


% % Duplicate sequence number.<br>

%Failed to add ace to access-list<br>
% % Duplicate sequence number.<br>

%Failed to add ace to access-list<br>
% % Duplicate sequence number.<br>

%Failed to add ace to access-list<br>
% % Duplicate sequence number.<br>

%Failed to add ace to access-list<br>
% % Duplicate sequence number.<br>

%Failed to add ace to access-list<br>
% % Duplicate sequence number.<br>

%Failed to add ace to access-list<br>

Switch><br>