```
1.0000000000000000001
1.000000000000000000
```
It's precision of display.... 

Have you learned C or C++? It's like:
```
printf("%.3d",1.000001);
```
If you mean:
```
1.0000000000000000001==1.0000000000000000000
```
It's because the default precision has only ten numbers, You need use`setPrecision` or like
```
1.0000000000000000001`22==1.0000000000000000000`22
```
There is refered in Possible Issues  (https://reference.wolfram.com/language/ref/Equal.html)

(If you think my English is poor, it's because I'm not native English speaker....