Speed of eth interfaces differ under the same bonding

I have recently noticed that one of the bonded eth interfaces [eth0] under the bond0 has 100mbps speed while the other one [eth4] has come up with 1000mbps speed. Auto-negotiation is on on both slave interfaces. I turned off and on auto-neg on eth0 at the prospect of advertising the correct speed, but it was of no avail.

Is there any other way to make this happen?

Here are configurations of the interfaces:

bond0

cat /etc/sysconfig/network-scripts/ifcfg-bond0
# Please read /usr/share/doc/initscripts-*/sysconfig.txt
# for the documentation of these parameters.
BOOTPROTO=static
ONBOOT=yes
DEVICE=bond0
NOZEROCONF=yes
NETMASK=255.255.255.0
NM_CONTROLLED=no
IPADDR=10.138.132.5
BONDING_OPTS='mode=1 miimon=100'

eth0

ONBOOT=yes
DEVICE=eth0
MASTER=bond0
NM_CONTROLLED=no
USERCTL=no
SLAVE=yes

eth4

ONBOOT=yes
DEVICE=eth4
MASTER=bond0
NM_CONTROLLED=no
USERCTL=no
SLAVE=yes

link_mode

cat link_mode 
0

ethtool bond0

ethtool bond0
Settings for bond0:
        Supported ports: [ ]
        Supported link modes:   Not reported
        Supported pause frame use: No
        Supports auto-negotiation: No
        Advertised link modes:  Not reported
        Advertised pause frame use: No
        Advertised auto-negotiation: No
        Speed: 1000Mb/s
        Duplex: Full
        Port: Other
        PHYAD: 0
        Transceiver: internal
        Auto-negotiation: off
        Link detected: yes

ethtool eth0

ethtool eth0
Settings for eth0:
        Supported ports: [ TP ]
        Supported link modes:   10baseT/Half 10baseT/Full 
                                100baseT/Half 100baseT/Full 
                                1000baseT/Half 1000baseT/Full 
        Supported pause frame use: No
        Supports auto-negotiation: Yes
        Advertised link modes:  10baseT/Half 10baseT/Full 
                                100baseT/Half 100baseT/Full 
                                1000baseT/Half 1000baseT/Full 
        Advertised pause frame use: Symmetric
        Advertised auto-negotiation: Yes
        Link partner advertised link modes:  10baseT/Half 10baseT/Full 
                                             100baseT/Half 100baseT/Full 
                                             1000baseT/Half 1000baseT/Full 
        Link partner advertised pause frame use: No
        Link partner advertised auto-negotiation: Yes
        Speed: 100Mb/s
        Duplex: Full
        Port: Twisted Pair
        PHYAD: 1
        Transceiver: internal
        Auto-negotiation: on
        MDI-X: off
        Supports Wake-on: g
        Wake-on: g
        Current message level: 0x000000ff (255)
                               drv probe link timer ifdown ifup rx_err tx_err
        Link detected: yes

ethtool eth4

ethtool eth4
Settings for eth4:
        Supported ports: [ TP ]
        Supported link modes:   10baseT/Half 10baseT/Full 
                                100baseT/Half 100baseT/Full 
                                1000baseT/Half 1000baseT/Full 
        Supported pause frame use: No
        Supports auto-negotiation: Yes
        Advertised link modes:  10baseT/Half 10baseT/Full 
                                100baseT/Half 100baseT/Full 
                                1000baseT/Half 1000baseT/Full 
        Advertised pause frame use: Symmetric
        Advertised auto-negotiation: Yes
        Link partner advertised link modes:  10baseT/Half 10baseT/Full 
                                             100baseT/Half 100baseT/Full 
                                             1000baseT/Half 1000baseT/Full 
        Link partner advertised pause frame use: No
        Link partner advertised auto-negotiation: Yes
        Speed: 1000Mb/s
        Duplex: Full
        Port: Twisted Pair
        PHYAD: 1
        Transceiver: internal
        Auto-negotiation: on
        MDI-X: off
        Supports Wake-on: g
        Wake-on: g
        Current message level: 0x000000ff (255)
                               drv probe link timer ifdown ifup rx_err tx_err
        Link detected: yes

IP and MAC addresses of [bond0] are shown on the access-layer switchport ARP-table as below: Switchport has 1000mbps speed.

#dis arp int vl 60
IP ADDRESS      MAC ADDRESS     EXPIRE(M) TYPE        INTERFACE   VPN-INSTANCE 
                                          VLAN/CEVLAN 
------------------------------------------------------------------------------

                                           583/-      
10.138.132.5    98f2-b33e-af30  4         D-0         GE3/0/36     

#dis int gig 3/0/36
GigabitEthernet3/0/36 current state : UP
Line protocol current state : UP
(omitted)
Speed : 1000,   Loopback: NONE
Duplex: FULL,   Negotiation: ENABLE
Mdi   : AUTO,   Flow-control: DISABLE