See comment (below) for clarification.

FULL PRODUCT VERSION :
java version "9"
Java(TM) SE Runtime Environment (build 9+181)
Java HotSpot(TM) 64-Bit Server VM (build 9+181, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 10.0.15063]

EXTRA RELEVANT SYSTEM CONFIGURATION :
No special configuration

A DESCRIPTION OF THE PROBLEM :
I defined a method and when i then called it, JShell offerred another one.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Enter in the JShell:

boolean equals(double d1, double d2) {
    return d1 == d2;
}
equals(.1+.2, .3)


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Method call returning false
ACTUAL -
jshell> equals(.1+.2, .3)
| Error:
| method equals in class java.lang.Object cannot be applied to given types;
| required: java.lang.Object
| found: double,double
| reason: actual and formal argument lists differ in length
| equals(.1+.2, .3)
| ^----^


ERROR MESSAGES/STACK TRACES THAT OCCUR :
  Error:
| method equals in class java.lang.Object cannot be applied to given types;
| required: java.lang.Object
| found: double,double
| reason: actual and formal argument lists differ in length
| equals(.1+.2, .3)
| ^----^


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
boolean equals(double d1, double d2) {
    return d1 == d2;
}
equals(.1+.2, .3)

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
I do not know

-------------------------------------------------------------

Workaround: use another method name