Incorrect ImageMobject Content

### Describe the bug
When I create a large number of ImageMobjects, some of them get incorrectly set to another ImageMobject's image. There should be 35 green checkmarks & 7 red crosses. However, one of the green checkmarks is replaced by the 8th cross.

**Code**:
```python
from manimlib import *

# Files: green.png, red.png in same folder as this script

class MyScene(Scene):
def construct(self):
nodes = [ImageMobject(f"./green.png") for i in range(35)] + [ImageMobject(f"./red.png") for i in range(7)]
network = Group(*nodes).arrange_in_grid().scale(0.2)
self.add(network)
```

**Wrong display or Error traceback**:

### Additional context
When I run this code on my laptop, I still get the wrong amount of each picture, but the incorrect one is in a different spot in the grid.