use of the same "dialer called 12345" in multiple dialer interfaces

Hi folks,

I have to use the same "dialer called 99885" in multiple dialer
interfaces for reaching the same application without screening the
customers number. In my example I can only receive one call for number
99885 at the same time. The first call was bind to dialer 501, the
second call tried to bind dialer 501 and was rejected. Why doesn't
reach the second call Dialer 500. That's my problem. I cannot receive
more than one call with the same numbers screened, regardless of
screening the CLI or DNIS. I cannot use rotary Interfaces, because I
have to send and receive different encapsulation over one E1
controller interface. Here my example:

interface Serial1/1:15
no ip address
encapsulation ppp
dialer pool-member 31
no snmp trap link-status
isdn switch-type primary-net5
no cdp enable

interface Dialer500
no ip address
encapsulation x25 dce
load-interval 30
dialer pool 31
dialer called 99885
dialer max-call 1
dialer-group 2
x25 htc 1
x25 win 7
x25 wout 7
no cdp enable

interface Dialer501
no ip address
encapsulation x25 dce
load-interval 30
dialer pool 31
dialer called 99885
dialer max-call 1
dialer-group 2
x25 htc 1
x25 win 7
x25 wout 7
no cdp enable

interface Dialer502
ip address 1.1.1.1 255.255.255.0
encapsulation ppp
load-interval 30
dialer pool 31
dialer called 99886
dialer string 12345678
dialer max-call 1
dialer-group 2
no fair-queue
no cdp enable


Thank you for your help!!!